"Simply Sinful" Cinnamon Muffins

I'm pretty sure I don't have to say much about these. Pretty much the ultimate cinnamon muffin here, and everyone loves cinnamon. Or should. The recipe comes from King Arthur Flour, a recipe for using it's Baker's Cinnamon Filling Mix, but I just used the butter-sugar-cinnamon substitution and they were AMAZING. Then I started reading some of the reviews of the cinnamon filling mix...and I'm pretty sure I'm gonna have to get me somma dat. Can you imagine all the nosh-worthy things a high quality cinnamon filling could go in? Dang. Simply sinful. (Like these muffins...)
Simply Sinful Cinnamon Muffins (print recipe)
Topping
1/3 cup brown sugar, packed
1/4 cup diced pecans
1/4 cup rolled oats
1/2 cup King Arthur Unbleached All-Purpose Flour
3 tablespoons soft butter

Filling
1/2 cup King Arthur Baker's Cinnamon Filling mix*
3 to 4 tablespoons water*

*Or substitute 3 tablespoons butter, 1/2 cup brown sugar, and 1 1/2 tablespoons ground cinnamon for the Baker's Cinnamon Filling mix and water, which is what I did.

Batter
1/2 cup (1 stick) butter, melted
3/4 cup milk
2 large eggs
1 3/4 cups King Arthur Unbleached All-Purpose Flour
1/2 cup rolled oats
2 tablespoons Signature Secrets(r) Culinary Thickener or cornstarch
3/4 cup granulated sugar
1 tablespoon baking powder
1/2 teaspoon salt
1/4 teaspoon ground nutmeg
1/2 cup cinnamon chips or butterscotch chips
1. Preheat your oven to 400°F. Line a 12-cup muffin pan with cupcake papers, or grease it lightly.

2. Prepare the topping by mixing the ingredients together until crumbly. Set aside.

3. Prepare the filling by mixing the Baker's Cinnamon Filling with enough water to make filling with a soft, pudding-like consistency. Set it aside. (Or make the filling substitute.)

4. To make the batter: In a large bowl, whisk together the melted butter, milk, and eggs. In a separate bowl, whisk together the dry ingredients, including the chips. Add the dry mixture to the liquid, stirring just until combined.

5. Divide half the batter evenly among the muffin cups. Dollop 2 teaspoons cinnamon filling onto each muffin, then top with the remaining batter. Sprinkle with topping, pressing it in lightly.

6. Bake the muffins for 20 to 25 minutes, or until they're golden brown. Remove them from the oven, and wait 5 minutes before transferring them from the pan to a rack to cool. Makes 12 muffins
Recipe from King Arthur Flour