Preheat oven to 375 degrees.
Place butter in a large mixing bowl and beat on high speed 30 seconds.
Add 1 c. sugar and baking powder and mix until combined.
Mix in egg & vanilla, then add flour a little bit at a time until fully incorporated. *Mixture may appear crumbly.
Using 2 Tbsp. dough at a time, form dough into balls and roll in granulated sugar.
Grease and flour two muffin tins.
Place balls in muffin tins. *No need to flatten; dough will spread during baking.
Bake at 375 degrees for 10-12 minutes.
Remove from oven; using the bottom of a small glass, gently press down the center of each cup to form a ridge.
Cool in pans 10 minutes, then remove to wire rack to cool completely.
Once cooled, top each cookie cup with lemon buttercream, 3-4 pieces Twizzlers Easter Grass Candy, and 3 jelly beans.