In a large mixing bowl, whisk together your almond flour, coconut flour, baking powder, brown sugar replacement, and salt.
In another medium bowl, beat your eggs with melted butter, almond milk, and vanilla extract.
Spread half of your batter into your prepared pan, and evenly spread half of your streusel on top. Top with remaining batter and then remaining streusel, slightly flatten your top layer of streusel so it sticks to your cake.
Once your coffee cake has cooled to room temperature, make your glaze by mixing your ingredients together, adding water until you get your desired consistency. Drizzle over top of cake and cut into 16 equal slices, enjoy!