01 -
Preheat oven to 350°F. Line a 9x13 inch metal pan with foil and coat thoroughly with non-stick spray. Avoid using a glass dish.
02 -
Combine unsalted butter and packed brown sugar in a mixing bowl and blend using a stand mixer or hand mixer until crumbly. Incorporate eggs and vanilla extract, mixing until the batter is smooth.
03 -
Add salt and baking powder, ensuring even distribution. Gradually mix in all-purpose flour until just combined. Gently fold in the M&Ms.
04 -
Transfer the dough to the prepared pan. Lightly coat your hands with cooking spray and use them to press and spread the dough evenly in the pan. Add any remaining M&Ms on top.
05 -
Bake for 22 to 25 minutes or until the top is just turning golden. Avoid overbaking to maintain a gooey texture, as residual heat will continue the baking process after removal.
06 -
Allow bars to cool completely in the pan. Slice into desired portions before serving. Store in an airtight container at room temperature for up to 4 days, or freeze for up to 1 month.