To make the muffins, preheat the oven to 350˚F. Line a 12-cup muffin pan with paper liners or spray lightly with oil.
Combine the Muffin Mix, cinnamon, and nutmeg in a large bowl. Whisk to combine. Add the water and oil. Whisk until well-combined.
Divide the mixture into the prepared baking pan, filling each cup about two-thirds full. Press a third of a Chewy Bar into the middle of each filled cup.
Bake for 20-30 minutes until golden brown and a toothpick inserted comes out clean. Let cool 10 minutes, then transfer each one to a wire rack to cool completely.
Once the muffins are cool, make the glaze. Combine the brown sugar, buttery spread, and milk in a small saucepan. Bring to a boil and let bubble for 1 minute. Remove from heat and add the confectioners’ sugar, whisking vigorously to combine. Stir in the vanilla extract. Let cool 10 minutes.
Dip each muffin into the glaze, putting them back onto the wire rack to let the glaze firm, about 5 minutes.
Serve, storing leftovers in an airtight container at room temperature for up to 2 days and any other leftovers in the freezer.