1. Preheat Oven and Prepare Pan: Setting the Stage for Baking

1. Preheat: Preheat your oven to 350°F (175°C).
2. Grease and Line Pan: Spray the bottom of an 8×8 inch baking pan with non-stick baking spray. Line the pan with parchment paper, allowing the sides of the parchment to overhang by an inch or two. This will make it easier to lift the brownies out of the pan after they’re baked.

2. Melt Butter, Chocolate, and Sugars: Creating the Rich Base

1. Set Up Double Boiler: Fill a medium saucepan with about 2 inches of water and bring it to a simmer over medium-low heat.
2. Combine Ingredients: In a heat-safe bowl (glass or metal), combine the unsalted butter, chopped semi-sweet chocolate, light brown sugar, and granulated sugar.
3. Melt Over Double Boiler: Place the heat-safe bowl over the saucepan, ensuring that the bottom of the bowl does not touch the simmering water. This is your double boiler setup.
4. Stir Frequently: Stir the mixture frequently with a heat-resistant spatula or wooden spoon until the butter and chocolate are completely melted and the sugars are dissolved. The mixture will be grainy but glossy.
5. Remove from Heat: Once everything is melted and smooth, remove the bowl from the heat and set it aside to cool slightly.

3. Incorporate Eggs: Adding Richness and Structure

1. Add Eggs One at a Time: Add the room-temperature eggs to the slightly cooled chocolate mixture, one egg at a time.
2. Whisk Well: Whisk well after each egg addition until it’s fully incorporated into the mixture.
   • Tip: Whisking vigorously at this stage helps to create a smooth and shiny batter.
3. Whisk Until Lightened: Continue to whisk the mixture for a few minutes until it lightens in color and becomes smooth and glossy.

4. Add Dry Ingredients and Vanilla: Completing the Batter

1. Add Cocoa Powder, Salt, and Vanilla: Add the Dutch-process cocoa powder, salt, and vanilla extract to the chocolate mixture.
2. Stir to Combine: Stir everything together until well combined. The batter will be thick and fudgy.

5. Fold in Flour: Gently Bringing it Together

1. Add Flour: Add the all-purpose flour to the batter.
2. Fold Gently: Using a large spatula, gently fold in the flour until just a few streaks of flour remain. Be careful not to overmix.
   • Tip: Overmixing can develop the gluten in the flour, resulting in a tough, cakey brownie.

6. Transfer to Pan and Top with M&M’s: Preparing for the Oven

1. Pour Batter: Transfer the brownie batter to the prepared 8×8 inch baking pan.
2. Level the Top: Use an offset spatula or the back of a spoon to spread the batter evenly in the pan and smooth the top.
3. Sprinkle with M&M’s: Sprinkle the M&M’s evenly over the top of the brownie batter. You can gently press them in slightly to ensure they adhere.

7. Bake to Fudgy Perfection: Achieving the Ideal Texture

1. Bake: Bake in the preheated oven for 45 to 50 minutes.
2. Check for Doneness: The brownies are done when the edges are set and a toothpick inserted two inches from the side of the pan comes out with just a few moist crumbs attached.
   • Tip: Do not overbake, or the brownies will be dry and cake-like instead of fudgy. It’s better to slightly underbake than overbake for fudgy brownies.

8. Cool and Cut: Patience Leads to Perfect Squares

1. Cool Completely: Remove the pan from the oven and place it on a wire rack to cool completely. This is essential for allowing the brownies to set and achieve their fudgy texture.
   • Tip: Cooling completely also makes them much easier to cut cleanly.
2. Slice: Once the brownies are completely cool, use the overhanging parchment paper to lift them out of the pan. Carefully peel off the parchment paper. Using a sharp knife, cut the brownies into squares of your desired size (typically 16 squares).