Add dry ingredients to the bowl of a stand mixer and stir until well combined. Add milk, vegetable oil, eggs, and vanilla and mix until well combined. Add boiling water, and mix on high speed for 1 minute.
Distribute batter between lined muffin tins and bake 20-25 minutes or until they test done with a toothpick.
Buttercream Icing
Beat butter until light and fluffy. Add extract, milk, and salt, then mix well. Gradually add powdered sugar and whip until fluffy. It may be necessary to add additional milk to reach your desired consistency.