3/4 cup butterscotch chips, plus additional to sprinkle on top
1 cup dark brown sugar, packed
2 teaspoons vanilla extract
Pre-heat oven to 350 degrees. Line 13 x 9 inch baking pan with aluminum foil, leaving overhang on all sides.
Mix flour, oats, baking soda, and salt in medium bowl until combined.
Heat butter in small pan over medium low heat until nutty brown in color, about 12 min.
Pour hot butter over butterscotch chips in large bowl and whisk until smooth. Whisk in brown sugar until dissolved, then whisk in egg and vanilla until combined. Stir in flour mixture in 2 additions until well combined.
Spread mixture in prepared pan and sprinkle with additional butterscotch chips, bake until edges are golden brown and a toothpick inserted in the center comes out with a few crumbs attached, 17-19 min. Transfer pan to wire rack. Cool until warm to the touch, about 1 ½ hours, then use foil over hang to lift the bars from the pan. Cool an additional 30 min, cut and serve. Enjoy!