Preheat the oven to 350°F (175°C). Line an 8" x 8" baking pan with parchment paper, leaving enough overhang to lift the cake out after baking.

In a medium bowl, stir together 2 cups super fine almond flour (packed and leveled), ¼ cup coconut flour (or, if you prefer, an additional 1 cup almond flour instead of the coconut flour), 2 tsp baking powder, and ½ tsp sea salt until evenly combined. Set aside.

In the bowl of a stand mixer fitted with the paddle attachment (or in a large mixing bowl with a hand mixer), combine 1 cup melted and cooled coconut oil and 1/3 cup sugar-free granulated sweetener. Beat briefly until the oil and sweetener are incorporated.

Add the 3 eggs and 1 tsp vanilla extract to the mixer. Beat on medium speed until the mixture is smooth and creamy.

Add the dry flour mixture to the wet ingredients and beat on medium speed until fully combined. The batter will be very thick—this is normal.

Make the streusel: In a separate bowl, stir together 2/3 cup almond flour, 1/2 cup chopped raw pecans, 4 Tbsp melted coconut oil, 2/3 cup sugar-free brown sugar, a pinch of sea salt, and 1 1/2 Tbsp ground cinnamon until the mixture forms coarse crumbs.

Transfer about half of the cake batter to the prepared pan. Press it into an even layer using a spatula or clean hands (dampen hands slightly if the batter sticks).

Sprinkle half of the streusel evenly over the first layer of batter.

Spoon the remaining batter over the streusel and spread/press it into an even layer. Sprinkle the remaining streusel evenly on top.

Bake on the center rack for 20 minutes. Remove the pan from the oven and tent loosely with aluminum foil (leave room for the cake to rise). Return to the oven and bake an additional 20–25 minutes, until the cake feels firm when gently pressed in the center.

Remove from the oven and let the coffee cake cool in the pan for at least 20 minutes. Use the parchment overhang to lift the cake from the pan, then slice and serve.