Heat sugar and butter in a medium pot over low heat until butter is completely melted, stirring often. Remove from heat, stir in 1 1/2 c. chocolate chips until melted, and let cool to room temperature.
In a small bowl, briefly whisk the eggs. Add 1 to 2 tablespoons of chocolate mixture to the eggs and stir to combine, just to temper the eggs. Then pour all of the eggs into the pot with the melted chocolate. Stir to combine.
Stir in flour, vanilla and baking soda until well blended. Grease a mini muffin tin or line with liners. Spoon about a tablespoon of brownie batter into each section; fill about 3/4 full. Bake at 350 degrees for 14 to 17 minutes, until fully cooked.
Let brownie bites cool completely before frosting.