- Butter your bundt pan, heavily. It may take more than two tablespoons. Place in freezer. 
- Mix together almond flour, coconut flour, salt, baking powder,  xanthan gum, Swerve granulated. Set aside. 
- Beat Eggs for 3 to 5 minutes. 
- Stream in melted butter. 
- Add lemon extract. 
- Add sour cream, lemon juice and zest. 
- Add dry mixture and mix just until mixed. Don't over mix.  
- Heavily butter bundt cake and freeze.  
- Pour batter into bundt pan only 1/4 way before adding blueberries. Add more batter and berries, but don't have any berries at the top, which ends up being the bottom of the cake. 
- Bake for 30 to 35  minutes at 325 degrees F., 180 C.  Use a meat thermometer to test the center of the cake which should be 207 degrees F.  
- Once out of the oven, set the timer for 15 minutes. Gently take a knife around the edges of the bundt cake. 
- After 15 minutes, take a knife again around the edges. Using a flat plate or cake board, using both hands flip cake over. Allow to cool before glazing.