01 -
Set oven to 375°F/190°C. Either grease your muffin tin or pop in paper liners before starting.
02 -
If using unsalted butter, toss in a pinch of salt. Whisk the flour and baking powder together in a medium mixing bowl.
03 -
In a big bowl, combine the sugar, eggs, and butter that you melted earlier. Stir in the milk, rum, and vanilla until smooth and light-colored.
04 -
Add the dry mix into the wet a bit at a time, folding gently. Don't overdo it—lumps are fine! Stir in the butterscotch chips at the end.
05 -
Scoop about 4 tablespoons of batter into each muffin tin slot. Sprinkle extra chips or sugar on top if you'd like. Bake for 20-24 minutes, checking with a toothpick—it should come out mostly clean.
06 -
Let muffins sit in the pan for 5-10 minutes, then move them to a rack to cool off. Serve them warm or at room temp, and you can brush some butter on top if you'd like.