Directions

Heat the oven to 400°F and grease the muffin pan or mini muffin pan.
Whisk the flour, salt, cream of tartar, and baking soda together in a medium bowl.
In a large bowl, cream the butter and sugar together.
Beat in the eggs, one at a time.
Stir in the milk and vanilla.
Add the dry ingredients and stir only until moistened.
Fill each cup about halfway.
Stir the topping sugar and cinnamon together and sprinkle it over the batter.
Bake regular muffins for 15 to 20 minutes and mini muffins for 10 to 12 minutes (about 7 minutes in a mini doughnut pan), until the tops crack and turn golden.
Serve warm, or let cool completely before storing or freezing.

Notes

Make-ahead mix: jar or bag with 2 cups flour, 1/2 teaspoon salt, 2 teaspoons cream of tartar, 1 teaspoon baking soda, 3/4 cup sugar; small separate bag with 1 tablespoon sugar and 1 teaspoon cinnamon. To bake from the mix: work 1 jar of mix with 1/2 cup softened butter until crumbly; add 2 eggs, 1 cup milk, 1 1/2 teaspoons vanilla; fill greased cups halfway; add topping; bake at 400°F as above.

Storage: airtight at room temperature up to 3 days, refrigerated up to 4 days, frozen up to 3 months; mix sealed in a cool, dry place up to about 6 months.

Nutrition

Nutrition is an estimate per serving from USDA FoodData Central, as cooked, 12 servings from the whole mix with 1/2 cup softened butter, 2 eggs, 1 cup milk, 1 1/2 teaspoons vanilla; milk counted as whole milk. Brands and portions vary, so use it only as an approximation.