Preheat oven to 350°. Line mini muffin pans with cupcake liners or spray with cooking spray (about 36). Set aside.

Stir 1/3 cup of the melted butter and cocoa in a large bowl. Add boiling water and hot coffee (you can substitute all water if you do not want to use coffee) and stir until the mixture thickens. Stir in sugar, eggs, and remaining butter and mix until smooth. Add flour, salt, and vanilla and blend completely. Scoop into prepared mini muffin pans.

Bake about 13 minutes, until they have a slightly glossy, rounded top. Cool completely before frosting.

Whisk flour into milk in a small saucepan over low heat. Stir constantly until it thickens. It should be very thick, like brownie mix. Remove from the heat and let cool completely to room temperature. (I sped this process along by placing the pan in a bowl filled with ice.) Stir in vanilla.

While the mixture is cooling, cream the butter and sugar together until light and fluffy. Make sure you beat it until there is no graininess left from the sugar. Then add the cooled milk/flour mixture and beat it. A lot! If it looks separated, you haven’t beat it enough. It’ll resemble thick whipped cream.

Taste it. Die and go to heaven.

Hurry up and frost the brownie bites or cake or whatever you’re frosting before you eat it all with a spoon.