Preheat oven to 425°F Spray or line with paper cups a 12-count muffin tin. Set aside.
In a large bowl, whisk the flour, granulated sugar, brown sugar, poppy seeds, baking powder, baking soda, and salt together until thoroughly mixed. Set aside.
In a medium bowl, whisk the melted butter, lemon and orange juices, lemon and orange zests, together until combined.
Add the eggs, one at a time, whisking after each addition. Whisk in the yogurt and vanilla. Pour the wet ingredients into the dry ingredients and gently mix together until no pockets of flour remain. Do not over mix. The batter is extremely thick.
Spoon the thick batter into the muffin tins, filling them all the way to the top. Bake for 5 minutes at 425F degrees. Keeping muffins in the oven, reduce oven temperature to 375 F and continue to bake for 10-13 minutes longer until tops are lightly golden.
A toothpick inserted in the center should come out clean. Allow to cool for 10 minutes.
Muffins stay fresh in an airtight container at room temperature for up to 5 days.