Preheat oven to 350° F. Grease and flour a 12 x 18-inch jellyroll pan.
To prepare the cream cheese filling: In a medium-size bowl, beat cream cheese and sugar until smooth. Add egg and beat well. Add flour and beat until incorporated. Set aside.
In a medium-size saucepan over low heat, melt butterscotch chips and the butter, stirring occasionally until smooth. Remove from heat and beat in brown sugar until well blended. Allow to cool for 5 minutes.
Beat eggs one at a time into the butterscotch mixture. Add vanilla extract. Add dry ingredients, beating until well combined. Stir in walnuts. Pour the batter into prepared pan.
Drop the cream cheese mixture by teaspoonsful over the batter. Using a small knife, swirl the cream cheese mixture by teaspoonsful over the batter. Using a small knife, swirl the cream cheese into the batter, forming a decorative pattern. Bake for 25 to 30 minutes or until a cake tester inserted into the center of pan comes out with moist crumbs attached. Do not overbake. Allow to cool to room temperature, or overnight, before cutting and serving.Makes 24 (3-inch) brownies Source: