PREPARE THE BAKING PAN

1. Preheat the oven to 350°F.
2. Grease and flour a 9-inch springform pan and line the bottom with parchment paper. Set aside.

MAKE THE STREUSEL

1. Whisk together the gluten-free 1:1 flour, almond flour, granulated sugar, light brown sugar, and salt.
2. Add the melted butter and vanilla extract and stir to combine.
3. Add the oats and sliced almonds and stir until evenly incorporated. Place in the refrigerator until ready to assemble the cake.

MAKE THE FRANGIPANE

1. Place the butter and sugar in a mixing bowl and use an electric hand mixer or a stand mixer with the paddle attachment to beat together until light and creamy (~2 minutes).
2. Add the egg, vanilla extract, and almond extract and mix for ~30-60 seconds until combined.
3. Add the almond flour and salt and mix on low until combined. Set aside.

MAKE THE CAKE BATTER

1. Whisk together the gluten-free 1:1 flour, almond flour, baking powder, baking soda, and salt. Set aside.
2. Cream together the butter and sugar using an electric hand mixer or stand mixer with the paddle attachment until light and fluffy (~2-3 minutes).
3. Add the eggs, vanilla extract, and almond extract and continue to mix until incorporated.
4. Add the sour cream and mix to combine.
5. Add the dry ingredients to the bowl of wet ingredients and mix on low until combined. Then continue to mix for another 30-60 seconds until the batter becomes mostly smooth.

ASSEMBLE THE COFFEE CAKE

1. Transfer the cake batter into the prepared pan and smooth the top to create an even layer.
2. Dollop the frangipane over the cake batter and use an offset spatula or the back of a spoon to smooth to the edges and create another even layer.
3. Remove the streusel from the refrigerator and sprinkle over the frangipane layer.

BAKE THE CAKE

1. Bake on the center rack of the oven for 45-55 minutes (or until the sides of the cake and streusel are golden brown). Tent with foil halfway through to prevent the streusel from browning too quickly.
2. Remove from the oven and allow to cool in the pan for about 15-20 minutes. Then gently run a knife between the cake and the pan and release the spring/remove the sides of the pan.
3. Allow the cake to cool to room temperature and then dust with powdered sugar. Slice and enjoy!