In a medium bowl whisk together flour, baking soda, baking powder and salt.
In your stand mixer cream together butter and sugar until light and fluffy. Beat in egg until combined.
Add vanilla and yogurt and mix well (it will look almost like cottage cheese - this is FINE and normal!)
Add flour mixture a little bit at a time to the wet mixture on medium speed mix until well combined.
Press dough into a disc shape and wrap tightly in plastic wrap - chill for 1 hour in the fridge (or longer if you want to make the dough the day before).
Preheat oven to 350 °F - grease a rimmed baking sheet focusing on the sides and place a piece of parchment paper on it.
Roll dough into 1/2" large rectangle and press gently into your baking sheet. You will likely have a couple of gaps to fill - simply trim some of the dough and press to fit (see photos in step-by-step)
Bake in preheated oven for 12-14 minutes until the top is lightly golden. You do not want to over cook these bars or they will not be as soft and fluffy.