1. Preheat your oven to 400°F. Line a 12-cup muffin pan with cupcake papers, or grease it lightly.

  2. To make the topping: In a small bowl, mix together all the ingredients together until crumbly. Set aside.

  3. To make the filling: In another small bowl, mix together the melted butter, brown sugar, and cinnamon. Set aside and let the mixture rest for 15 minutes to thicken.

  4. To make the batter: In a bowl or large measuring cup, whisk together the melted butter, milk, and eggs.

  5. In a separate bowl, whisk together the dry ingredients, including the chips.

  6. Add the liquid mixture to the dry ingredients, stirring just until combined.

  7. Divide half the batter evenly among the muffin cups; a tablespoon cookie scoop, generously filled, works well here.

  8. Dollop 2 teaspoons of the filling onto each muffin; a teaspoon cookie scoop, filled level, works well here.

  9. Top with the remaining batter.

  10. Sprinkle generously with the topping, pressing it in lightly.

  11. To bake the muffins: Bake for 20 to 25 minutes or until the tops of the muffins are golden brown.

  12. Remove the muffins from the oven, and wait 5 minutes before transferring them from the pan to a rack to cool.

  13. To make the glaze: In a small bowl (re-use the bowl that had the topping in it to reduce clean up), mix the glaze ingredients together until smooth. Drizzle over the cooled muffins.