Preparation

Preheat oven to 375°F. Coat a 13 x 9-inch baking pan with nonstick cooking spray; line with parchment paper or aluminum foil leaving a one-inch overhang on either side.
Put the butter and chocolates into a heatproof bowl and place over a pot of simmering water.
1. Once both are completely melted, stir in the cocoa powder and set aside to cool to room temperature. Reserve.
2. Put the eggs and egg yolk into the Cuisinart®mixing bowl. Attach the flat mixing paddle and mix on Speed 3 until broken up and lightened, about 30 seconds. Add the granulated and brown sugars and beat on Speed 4 until light and thickened, about 1 more minute. Scrape the entire bowl as necessary.
3. Add espresso powder and vanilla extract; mix until well combined.
4. Combine the flours and salt and stir themixture into the melted chocolate and butter. Decrease speed to 2 and add the chocolate/ flour mixture. Mix until just combined, about 45 seconds. Scrape the entire bowl well.
5. Decrease speed to 1 and add the chocolate chips to fold in.
6. Pour into prepared pan. Bake until edges are dry, about 45 to 50 minutes. The brownies will still be “wet” inside.
7. Remove from oven and cool slightly in pan; then, using the parchment paper/foil overhang, lift brownies out of pan and transfer to a wire rack to continue cooling. Cut and serve warm if desired. Store remaining brownies in an airtight container.