Preheat oven to 350 F. Lightly grease a 9x13 baking dish. Set aside.
Stir together the butter, sugars, and vanilla in a large bowl until well-combined.
Stir in the eggs, one at a time, mixing well after each, until thoroughly blended.
Add the flour, cocoa powder, and salt in a bowl. Stir in until just incorporated.
Mix in the chocolate morsels.
Pour the batter evenly into the prepared baking dish.
Bake 20-35 minutes. The edges should look dry and set, but there should still have fudgy crumbs but not wet batter when a toothpick is inserted in the middle.
Cool in the pan to room temperature before cutting.
To avoid packing in the flour (and ending up with dry brownies), sift or stir the flour. Then lightly spoon it into the measuring cup. Avoid tamping it down or packing it in. Level the flour off with a butter knife.