Step 1

Preheat oven to 350°F. Lightly grease a 9-inch round aluminum cake pan with 2-inch sides and line it with a round of parchment paper. Set aside. See note for other sizes pans.

Step 2

Combine the brown sugar and butter in a small saucepan over medium heat. Cook, stirring until the butter and sugar are just melted, about 1-2 minutes. Mix in the vanilla bean paste and salt. Pour the caramel into the prepared cake pan.

Step 3

Arrange the halved bananas, cut-side down, over the caramel, squeezing in as many as will fit.

Step 4

Whisk together the sorghum flour, sweet rice flour, tapioca flour, teff flour, xanthan gum, cinnamon, baking powder, baking soda, and salt.

Step 5

In the bowl of a stand mixer fitted with the paddle attachment or a large mixing bowl with a hand mixer, cream together the butter and sugar over medium-high speed until light and fluffy, 3-5 minutes.

Step 6

Add the eggs, one at a time, mixing after each addition and scraping down the sides as needed. Add the vanilla extract.

Step 7

With the mixer on low, add the dry ingredients in three additions, alternating with the milk and sour cream, scraping down the sides as needed. Mix until just combined.

Step 8

Pour the cake batter over the bananas, smoothing out the top.

Step 9

Bake for 50-55 minutes, until the center springs back when gently touched and a toothpick comes out clean or with just a few crumbs.

Step 10

Let cool In the pan for 10 minutes (but no longer or the caramel will firm up and stick to the pan!). Run a knife around the outside edge, place a wire rack over the top and, holding the wire rack and cake pan together with oven mitts, carefully flip the cake right-side up, setting it over a plate or baking sheet to catch any caramel spills. Spoon any caramel left in the pan over the top, and if any banana bits remain stuck to the top, carefully put them back on the cake. Let cool for at least 30 minutes before slicing and serving.