In the bowl of a stand mixer, cream butter, sugars and lemon zest until fluffy. Beat in the eggs, sour cream and vanilla until smooth.
In a separate bowl, whisk together the flour and baking powder. Add the flour mixture into the wet ingredients and beat until just combined.
Form the dough into 2 discs, wrap in plastic and chill for at least 30 minutes. (You can also freeze the dough for future use.)
Preheat oven to 350 degrees. Line a baking sheet with parchment paper. Roll the dough onto a well-floured surface until it reaches 1/4 inch thickness. Cut into shapes and place on prepared baking sheet.
Bake 12-14 minutes. Cookies will be pale with a slightly golden bottom. Allow cookies to cool on the baking sheet 5 minutes before removing onto a cooling rack.