Preheat the oven to 350 F. In a large bowl, whisk together flour, sugar, cocoa powder, salt, and baking soda. Add in the eggs, melted butter, and vanilla extract until smooth.
Pour half of the brownie batter into a greased 8-inch square baking dish. Place the Rolos evenly on the batter. Cover with the remaining half of brownie batter. Bake for 20-25 minutes.