Preheat the oven to 350 F. Line a 12 cup muffin pan with paper liners. 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.
Evenly divide half of the brownie batter between the paper liners. Place one Rolo on each brownie cup. Cover with the remaining brownie batter. Bake for 15-20 minutes.