My Secret Less-Sweet, Fluffy Vanilla Frosting

Bahan-bahan (12 porsi)

• 5 tbsp flour (, plain/all purpose)
• 1 cup white sugar (, regular/granulated (can reduce to 1/2 cup, Note 1))
• 1 cup milk, warmed using any method (, full fat best (but even 0% fat works))
• 1 1/2 tsp vanilla extract
• Pinch of salt
• 225 g / 1 cup unsalted butter (, softened but not too soft! (Note 3))
• 1/4 cup cocoa powder, unsweetened ((Dutch processed best, if you can))