1Preheat oven to 350 degrees F (175 degrees C). Grease an 8x8 baking dish with 1 teaspoon butter.
2Whisk 1 cup sugar and melted butter together in a bowl. Add vanilla, cocoa powder, salt, food coloring, vinegar, and eggs to sugar mixture, blending well after each addition.
3Stir flour into sugar mixture until batter is just combined. Pour batter into prepared baking dish, reserving 1/3 cup batter for cream cheese layer.
4Blend cream cheese, 1/4 cup sugar, egg, and vanilla extract together in a bowl. Spread cream cheese mixture over brownie batter in the prepared baking dish. Pour reserved 1/3 cup brownie batter in 2 rows over cream cheese layer. Pull a knife through the batter rows into cream cheese layer to form swirls.
5Bake in the preheated oven until a toothpick inserted into the center comes out clean, 30 to 35 minutes. Cool completely before slicing.