Preheat oven to 350F. Line an 8X8 pan with parchment paper, leaving some overhang to lift cake out once baked
In a large bowl, combine lemon zest with sugar. Use your hands to rub the zest into the sugar and express the oils in the peel.
In a separate small bowl, combine the 2 cups of blueberries with 2 tablespoons of flour and mix until the berries are completely covered in flour. Set aside
In the bowl of a stand mixer or large bowl with a hand mixer, cream butter, sugar and lemon zest.
After 3 minutes (this will take longer with a hand mixer) mixture should be light and fluffy. Add in the egg and vanilla bean paste. Mix again
Add in yogurt and sour cream to the mixture and mix again until combined
In a small separate bowl, combine all dry ingredients (flour, baking powder, salt) and whisk to combine
Add all dry ingredients into a larger bowl and mix until a thick batter forms
By hand, add in the blueberries and mix. The batter will be very thick.
Spread batter into the parchment-lined pan using an offset spatula
Sprinkle 1/3 cup sugar on top of the evenly spread batter
Bake for 40-50 minutes, or until a knife inserted through the center comes out clean
Remove from oven and let cool for 20 minutes before cutting
