Preheat oven to 350°F. Spray 8x8-inch pan with avocado oil spray.
Stir together brownie mix, water, eggs and melted butter in a large bowl until well blended, about 50 strokes.
Spread into pan and bake 24 to 28 minutes, until toothpick inserted in center comes out clean. Cool completely on wire rack.
Beat cream cheese, peanut butter and confectioners' erythritol in a medium bowl with an electric mixer on low speed until blended, about a minute. Beat on medium speed until smooth and creamy, about 2 minutes.
Spread peanut butter icing over brownies. Cut keto friendly brownies into 12 squares and enjoy!