In a small or medium mixing bowl, stir together the flour, cocoa powder and salt. Set aside.
1/4 cup + 2 tbsp (46 grams) flour, 1/4 cup + 2 tbsp (43 grams) natural cocoa powder, 3/8 teaspoon salt
After about 10 minutes of pie crust chill time, melt the butter in a large microwave-safe mixing bowl in the microwave. I usually do 30 seconds at full power, then start doing 15-second increments, stirring after every one. But you can melt it however you normally melt butter in the microwave.
3/4 cup (168 grams) unsalted butter
To this bowl of warm butter (but it shouldn’t be so hot that it cooks the eggs), stir in the granulated sugar, eggs, and vanilla just until combined.
1 1/3 cups (266 grams) granulated sugar, 3 large eggs, 2 teaspoons vanilla extract
Stir in the flour and cocoa mix just until no more streaks of flour remain.
Fold in 1 cup of regular-sized chocolate chips.
1 cup (170 grams) semi-sweet chocolate chips
Pour the filling into the chilled, unbaked pie crust and use a silicone spatula to spread it even.