Preheat the oven to 350ºF. Line 30 muffin cups with paper liners.

In a large bowl, beat the cake mix, water, oil and eggs on low speed for 1 minute. Add the bananas and rum extract and beat on medium speed until combined, about 30 seconds. Fill each cup 3/4 full.

Bake in the preheated oven until a tester inserted in the center comes out clean, 18-23 minutes. Cool in the pans for 10 minutes, then remove to a cooling rack to cool completely.

Once cool, cut a cone shape about 3/4” in diameter and 3/4” deep with a sharp paring knife. Cut off the pointed end of the cone and reserve the top. Fill each hole with about 1 teaspoon of the dulce de leche, then cover with the reserved tops.

To make the frosting, beat the butter with an electric mixer on medium-high heat until light and fluffy. Add the powdered sugar slowly, beating on low. Once all of the sugar has been added, beat on medium for 1 minute. Add 3 tablespoons of the milk and the rum extract. Beat until light and fluffy. If the frosting is too thick, add a little more milk until you reach the desired consistency. Add food coloring and beat in, if desired.

Pipe the frosting on top of each of the cupcakes. Serve immediately or refrigerate until ready to serve.