Preheat oven to 350°F and line a large baking sheet with a nonstick silicon mat or parchment paper.

In a medium bowl, whisk together flour, ¼ teaspoon salt, baking soda and espresso powder. Set aside.

In a large microwave safe bowl, combine butter and 1 cup chocolate chips. Heat for 30 seconds and stir. Heat in 15 second increments, stirring after each, until melted, smooth and combined.

Add sugar and cocoa powder and stir to combine.

Add egg whites and vanilla, and stir again to combine.

Add flour mixture to chocolate mixture and stir until completely combined.

Add ⅓ cup toffee bits and 2 tablespoons mini chocolate chips and stir to combine.

Use a spatula to spread the batter in an event, thin layer on prepared baking sheet.

Sprinkle the top with remaining ½ teaspoon salt, ⅓ cup toffee bits and 2 tablespoons mini chocolate chips.

Bake for 15 minutes or until it's cooked through (like a normal brownie consistency). Remove from the oven and carefully slice into squares and/or triangles.

Turn off the oven and place the brownies back into the oven and let them continue to bake as the oven cools. Check in every 5 minutes to make sure they're not burning - you want them to crisp, not burn!

Remove from oven and let cool completely before serving and/or storing. Enjoy!