Preheat oven to 350. Line an 8 inch square pan with nonstick foil or parchment.
Combine the flour, baking powder and salt and set aside.
Stir the warm melted butter and brown sugar together in a mixing bowl. Add the egg and vanilla and mix until smooth. Stir in flour mixture until blended, then add oats, and butterscotch chips.
Spread batter evenly in the prepared pan and bake for 25 minutes or until edges are browned and top appears set.
Let cool to room temperature, then put the bars in the refrigerator (optional, but recommended) to chill. Lift from pan and cut into 8 bars or 16 squares.
Sprinkle with sea salt before serving.