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