Start by preheating your oven to 350°F (177°C). Grab three 6-inch round cake pans (or two 8-inch ones) and give the sides a good spray with baking spray. Line the bottoms with parchment paper circles so nothing sticks—easy cleanup later!

In a medium bowl, whisk together the flour, baking powder, baking soda, cinnamon, and salt. Set that aside for now—dry team’s ready to go!

Now for the bananas. You’ve got two options: mash them up with a fork right on your cutting board or let your stand mixer do the work. Just pop them in the bowl with the paddle attachment and mix on low until they’re smooth. No need to clean the bowl afterward—you’re using it next anyway!

Add the butter, granulated sugar, and brown sugar to the same mixing bowl and beat on high speed until it’s nice and fluffy—about 2 minutes. Don’t forget to scrape down the sides of the bowl. Now mix in the eggs and vanilla on medium-high speed until everything’s combined. Toss in those mashed bananas and give it a quick mix. It might look a little weird and curdled right now, but don’t panic—it’s totally normal!

With the mixer on low, start adding the dry ingredients in three parts, alternating with the buttermilk. Mix just until it all comes together—no overmixing! The batter will be slightly thick and that’s exactly what you want.

Evenly divide the batter between your prepared pans and pop them in the oven. Bake for 30–35 minutes, or until a toothpick inserted in the center comes out clean. Let the cakes cool in the pans for about 5 minutes, then turn them out onto a wire rack and let them cool completely—give it a couple hours to be safe.

First, set aside 2 sticks of unsalted butter to come to room temperature while you get started. You’ll use the other 2 sticks to make some amazing browned butter — yum!

To brown the butter, toss those 2 sticks into a large frying pan over medium heat. Let it melt, stirring now and then. After it’s melted, keep stirring constantly for another minute or two. You’ll notice it starts to foam, then turn a lovely light brown color and smell nutty and delicious. That’s your cue to take it off the heat. Pour the browned butter into a glass container and let it chill out — either leave it on the counter for about 2 hours or pop it in the fridge for 30 minutes. You want it thick and at room temp, kind of like caramel, before moving on.

Once your browned butter is ready, grab the 2 sticks you set aside earlier. Put them in your stand mixer bowl with the paddle attachment and beat on medium-high for about 5 minutes until the butter is creamy, light, and fluffy. Don’t forget to scrape down the sides so everything mixes evenly!

Now, add in the cooled browned butter and vanilla extract. Mix on medium speed until everything is smooth and combined. Turn the mixer down to low and slowly add the powdered sugar — a little at a time — scraping the bowl and paddle after each addition so it blends perfectly. Finally, pour in the milk and salt, and mix on low until silky smooth and dreamy.

Got everything ready? Great—because you’ll be stirring nonstop! Start by putting the sugar into a medium saucepan over medium-high heat. Keep that wooden spoon moving constantly as the sugar melts into a beautiful amber liquid—no lumps allowed! This usually takes about 5 to 6 minutes.

Once you’ve got that gorgeous caramel color, turn the heat down to medium. Now, carefully add the butter—heads up, it’ll bubble up a bit! Whisk it in until the butter melts completely and blends smoothly with the sugar, about 2 to 3 minutes.

Next, slowly pour in the heavy whipping cream while whisking away. Once it’s all combined, let the caramel bubble up for a full minute, then take it off the heat and stir in a pinch of salt.

Let your caramel cool to room temperature if you’re mixing it into buttercream or using it as a cake topping. If you just want to drizzle it over ice cream or warm treats, letting it cool for about 20 minutes will do the trick—it will thicken as it cools, getting even more delicious!

Once your banana cake layers have completely cooled, it’s time to level them out and slice each layer to your perfect height. Start by placing the first layer on a turntable. Now, pipe a circle of brown butter frosting around the edge—think of it like building a little frosting fence (this is called a buttercream dam). Inside that frosting ring, spoon in a thin layer of salted caramel. Then, fill the rest of the space inside the “fence” with more brown butter frosting. Yum! Now gently add the next cake layer on top.

Repeat the same fun process for the next layer: pipe your frosting ring, add salted caramel, and fill the center with more frosting. For the final cake layer, flip it upside down so the bottom becomes the top—this gives a nice flat surface. Time for a crumb coat! Spread a thin layer of brown butter frosting all over the cake to lock in those crumbs, then pop it into the fridge for at least 20 minutes to chill and set.

To get that pretty cake look from the picture, smooth on another layer of brown butter frosting all around. Then, grab some Biscoff cookie crumbs and press them gently onto the bottom third of the cake. Back into the fridge it goes for about 30 minutes—this cold base helps the salted caramel drip look perfect.

While the cake chills, warm up the salted caramel in the microwave for short 5-10 second bursts until it’s just a little warmer than room temp and flows nicely for dripping (if you want a handy guide, check out this post on perfect drip consistency with chocolate ganache—it’s the same idea!). Once your cake is chilled and the caramel is just right, drizzle that gorgeous caramel drip all around the edges. Then, chill again for 10 minutes so the caramel can set up beautifully.

For the grand finale, fit a piping bag with a Wilton 1M tip and fill it with the leftover brown butter frosting. Pipe lovely swirls spaced about a quarter-inch apart all over the top of the cake. Between each swirl, tuck in a banana slice, then sprinkle more Biscoff cookie crumbs on top for that extra wow factor.