Whisk flour and half and half together to combine and remove any lumps. I used my Nutra Bullet to make combining these two ingredients easier, but you can use a whisk or a blender. Even an immersion blender should work.

Put combined liquid into a medium size saucepan and cook over medium heat until mixture begins to boil, whisk constantly until it thickens.

Cool completely before adding to the butter and sugar. I put my flour mixture into a shallow dish and put in the fridge while I continued making the icing.

Combine white sugar with cinnamon in small bowl. Place butter and cinnamon sugar in bowl of stand mixer

Beat on medium high with paddle attachment until the sugar combines with the butter and is no longer gritty. Scrape the sides of your bowl often. This takes about 5 minutes.

Add the cooled flour mixture into the butter/sugar mixture.

Whisk on high until the mixture comes together and beings to look like whipped cream.