Preheat the oven to 350 degrees F and line a 8” x 8” baking pan with parchment paper.

In a bowl, stir together the almond flour, coconut flour, baking powder, and sea salt until well combined.

Add the melted coconut oil to a stand mixer fitted with a paddle attachment, along with the sugar-free granulated sweetener. Beat until well combined.

Add the eggs and vanilla extract to the mixer and beat on medium-high speed until well-combined and a creamy, custard-like mixture forms.

Add the flour mixture to the mixer and beat on medium-high until completely combined. Note: The cake batter will be very thick. This is normal!

Stir together the ingredients for the streusel topping in a mixing bowl until well-combined.

Transfer half of the cake batter to the parchment-lined baking pan and press it into an even layer (I do this with my hands).

Sprinkle half of the streusel topping evenly over the cake batter. Repeat with the other half of the cake batter and the remaining topping.

Bake on the center rack of the preheated oven for 20 minutes. Remove the coffee cake from the oven, cover it in foil (be sure to tent the foil to leave room for the cake to grow), and bake another 20 to 25 minutes, until the coffee cake feels firm when gently poked in the center.

Allow coffee cake to cool at least 20 minutes before slicing and serving.