Allow butter and eggs to stand at room temperature for 30 minutes.

In a medium bowl combine flour, baking powder, and salt. In a small bowl, mix together brown sugar, cinnamon, and pecans. Set both aside.

Preheat oven to 350 degrees F and line 24 muffin cups with cupcake liners.

In a large mixing bowl, beat butter on medium speed for 30 seconds. Add sugar 1/4 cup at a time, scraping sides of the bowl occasionally. Beat for 2 minutes more until light and fluffy. Add eggs, one at a time, beating well after each addition. Beat in vanilla. Add flour mixture and milk in alternating additions, beginning and ending with the flour; beat on low speed after each addition just just combined (batter may look curdled).

Spoon 1 tablespoon batter into the bottom of each muffin tin. Sprinkle 1 teaspoon brown sugar mixture over batter in each cup. Repeat, spooning 1 tablespoon batter, then 1 teaspoon brown sugar mixture into each muffin tin.

Bake for 18 to 20 minutes or until a toothpick inserted in the center comes out clean. Cool cupcakes in cupcake pan on wire rack for 10 minutes. Remove cupcakes from tin and cool completely on wire racks.

While cupcakes cool, prepare buttercream.

Beat butter in large mixing bowl for 1 minute until fluffy. Beat in confectioner’s sugar 1 cup at a time until well combined with butter. Add extracts. Add milk, 1 tablespoon at a time, until desired frosting consistency is achieved.

Pipe frosting onto cooled cupcakes with a star tip. While frosting is wet, sprinkle cupcakes with yellow, purple, and green sanding sugar (one third of the cupcake top per color). Gently shake off extra sugar once frosting has set. Top with Mardi Gras themed cupcake pick if desired.