Combine 2 oz all purpose flour, 8 oz granulated sugar and ½ teaspoon salt in a saucepan, whisk to combine. Slowly whisk in 8 oz whole milk until smooth. Heat the mixture over medium low, whisking constantly, until it begins to boil.
Continue to cook and stir for 2-3 minutes until it thickens to a pudding-like texture. Immediately remove from the heat. Sift 1 ½ oz malted milk powder and 1 oz cocoa powder over the pudding and whisk until smooth. Transfer to a bowl. Add 2 teaspoons vanilla extract and cool to room temperature.
Cream 8 oz unsalted butter until light and fluffy. Add the pudding, a little at a time, until completely incorporated. Switch to the whisk attachment and whip the buttercream until it’s light and fluffy.
Use immediately to fill and frost your favorite cake.
Notes
One batch of frosting is enough to fill and frost a 9" round cake.