Preheat the oven to 350 °F (177 °C) then line an 8x8-inch baking pan with parchment paper.
Make the brownies by whisking together the flour, cocoa powder, baking powder and salt in a large bowl then setting aside.
1 ⅓ cup all-purpose flour, ¾ cup cocoa powder, ¾ teaspoon baking powder, ½ teaspoon kosher salt
Whisk the eggs, butter, granulated sugar, brown sugar and vanilla extract together in a separate large bowl until smooth then pour it gradually into the dry ingredients and mix just until there are no more lumps.
3 eggs, 1 cup unsalted butter, ½ cup granulated sugar, ½ cup light brown sugar, 1 teaspoon pure vanilla extract
Stir in the chocolate chips then pour the mixture into the prepared baking pan and bake for 20 minutes.
1 cup semisweet chocolate chips
While the brownies are baking make the pecan pie later by melting the butter in a large saucepan over medium heat.
2 tablespoons unsalted butter
Add the eggs, brown sugar, white sugar, corn syrup and vanilla and whisk continuously over medium heat until it starts to thicken, about 15 minutes.
2 eggs, ¾ cup dark brown sugar, ½ cup white sugar, ½ cup light corn syrup, 2 teaspoons pure vanilla extract
Whisk in the heavy cream, be careful because it may start to bubble.
¼ cup heavy cream
Stir in the pecans then pour it over the half-baked brownies.
2 cups chopped pecans
Bake for another 20-25 minutes or until the center is only slightly jiggly.
Let them cool for about 1 hour then slice and serve.
Notes
These brownies can be stored in an airtight container for up to five days.