Add in the cold butter pieces and cut the butter into the mixture using your fingers or a fork until it looks like wet sand. Place the bowl in the fridge while you make the muffin batter.

In a medium bowl, combine the flour, salt, baking soda, and baking powder. Whisk together and set aside.

In a large mixing bowl, add the sugar and eggs. Beat together on high speed with a hand mixer for about one minute. Add the oil, milk, Greek yogurt, and vanilla extract. Mix until fully combined.

Add the dry ingredients into the wet ingredients and stir until just combined. Remove the cinnamon mixture from the fridge and add it to the batter. Very gently fold it in, only about 3-4 folds. You do not want it fully mixed in. Those streaks of cinnamon are what you are going for.

Divide the batter evenly into the muffin liners. The batter will come close to the top of each tin, that is okay.

Bake at 400 degrees for 5 minutes, then reduce the heat to 350 degrees F and bake for an additional 15-18 minutes, or until the muffins are fully set and a toothpick comes out clean. Remove from the oven and let cool completely.

While the muffins are cooling, make the cream cheese frosting. Beat the softened butter and cream cheese together on high speed until smooth. Slowly add the powdered sugar, beating it in fully before adding more. Mix in the vanilla extract.

Pipe or spread the cream cheese frosting onto the cooled muffins and enjoy!