Preheat the oven to 350 F. In a large bowl, whisk together flour, sugar, cocoa powder, salt, and baking soda. Add in eggs, melted butter, and vanilla extract, and mix until smooth.
Using a cookie scoop, place the brownie batter onto a large ungreased baking sheet at least 2-inches apart. Bake for 10-12 minutes.
Remove from the oven and decorate the brownie cookies with pretzels, chocolate chips, and m&ms.