Preheat the oven to 350°F. Line a 12-cup muffin pan with cupcake liners. Line a second pan with 8 liners – this recipe makes about 20 cupcakes.
Whisk together the flour, baking powder, salt, and baking soda.
Using a stand mixer fitted with the paddle attachment or a hand mixer, cream the butter and sugar until fluffy and pale yellow.
Mix in eggs one at a time. Then, add in the the vanilla.
Alternate incorporating the dry ingredients and buttermilk to the butter mixture, beginning and ending with flour mixture. Mix until just combined.
Pour or spoon the batter into the prepared muffin tins, filling each liner 2/3 full. Bake at 350°F for 18-20 minutes or until a toothpick inserted in the center comes out clean.
While the cupcakes are baking, prepare the butter glaze.
Heat butter, sugar, and water over medium low heat until butter is melted and sugar is completely dissolved. Remove from heat and stir in vanilla.
After cupcakes are removed from oven and still warm, move cupcakes to a cooling rack and place over a cookie sheet or parchment paper to catch any drips. Thoroughly poke holes in each one using a toothpick or skewer and spread butter glaze over each cupcake being sure to fill the holes. Add glaze in small amounts to give it time to soak in.
Right before serving, use a fine sieve to dust the top of each cupcake with confectioners' sugar.