Melt the butter in a small pan or medium microwave-safe bowl. Add the sugar. Heat over low heat or microwave on low power until warm. Don’t let the mixture bubble. Stir gently. Add the chocolate chips and stir until the chocolate melts. If needed, heat the mixture over low heat to fully melt the chocolate.
Pour the mixture into a medium bowl. Let cool for about three minutes. Stir in eggs until smooth. (Add vanilla now, if using) Add gluten-free flour, cocoa powder, and salt. Mix until smooth. Stir in nuts or chocolate chips if using.
Spread batter into prepared pan.
Bake for about 30 minutes. Or until a toothpick inserted comes out clean or with just a few crumbs on it.
Cover brownies and store on the counter for up to four days.
To freeze: Wrap cooled brownies or place into a freezer container. Freeze up to three months.
For Gluten-Free and Dairy-Free Brownies: Replace the butter with a dairy-free butter replacement. Use dairy-free chocolate.