Step 1

Preheat the oven to 350°F. Line a 9-inch round (or 8-inch square) cake pan with parchment paper. Grease the paper and any exposed parts of the inside of the pan.

Step 2

Whisk together the flour, baking powder, and salt. Set aside.

Step 3

Using an electric mixer on medium speed, beat the butter and sugar until light and fluffy. Add the eggs, one at a time, mixing well after each addition. Mix in the Irish cream and vanilla.

Step 4

Reduce mixer speed to low. Add the flour mixture in three portions, alternating with two portions of milk. Mix just until combined.

Step 5

Transfer the batter to the prepared pan and spread evenly. Tap the pan gently a few times on the counter to get rid of any large air pockets.

Step 6

Bake the cake 35 to 40 minutes, or until the cake is golden brown and a pick inserted into the center comes out clean.

Step 7

Place the pan on a wire rack and allow the cake to cool.

Step 8

Using an electric mixer on medium speed, beat the butter until fluffy.

Step 9

Gradually add the confectioners' sugar, and mix well.

Step 10

Add the Irish cream, vanilla, and salt. Mix at medium-high speed until the frosting is smooth and fluffy. If needed, add a little bit of milk to the frosting to get it to a smooth, spreadable consistency.

Step 11

Spread the frosting on the cooled cake. Add any garnishes you like.