Prepare the brownies: Preheat oven to 350F. Line a medium cookie sheet with nonstick tin foil. Set aside.
Melt butter and chocolate chips in a medium saucepan over medium heat until smooth. Remove from heat and set aside to cool slightly.
In a large bowl, whisk eggs, sugar, vanilla and cooled chocolate mixture. Gently whisk in flour, cocoa, and salt until just combined. Pour batter into prepared pan and smooth with a spatula.
Bake brownies at 350F 10-15 minutes or until a toothpick comes out with moist crumbs sticking to it. (brownies may puff up in the middle---this is ok)
Cool brownies completely on a wire cooling rack, then use a 4-in biscuit cutter to cut out 15 circles. Set aside while you prepare the frosting.
Make the frosting: Place cream cheese and butter in a medium bowl. With a handheld electric mixer, beat on medium speed until creamed. Beat in sugar, vanilla and just enough milk to achieve a creamy, spread-able consistency.
Assemble the pizzas: Spread cream cheese frosting over cooled brownie "crusts" and then generously top with sliced strawberries and blueberries.
Pizzas are best if enjoyed immediately after assembling. Dig in!