Melt butter in a medium-sized, microwave safe bowl. Whisk in sugar before beating in eggs, one at a time. Add remaining ingredients and microwave at 1-minute intervals (usually about 3 minutes total) until the curd is thick enough to coat the back of a spoon. Chill until cold.

Combine milk and lavender buds in a blender or food processor. Macerate together, until the buds have broken down within the milk. Set aside.

Preheat the oven to 350 degrees F. Sift together flour, baking powder, and salt in a small bowl and set aside.

In a large mixing bowl, cream together butter, sugar, and vanilla bean paste. Beat in eggs one at a time. Slowly mix in dry ingredients, followed by the lavender milk. Beat until just incorporated; do not overmix.

Fill each cupcake liner ⅔ full. Bake for 12-15 minutes, until a toothpick inserted in the center comes out clean.

Allow cupcakes to cool completely.

Cut a 0.5-1 inch deep hole into the center of each cupcake. Place lemon curd into a pastry bag or Ziplock equipped with a piping tip. Pipe filling into the center of each cupcake. If desired, replace some of the cupcake filling before piping on icing.