Preheat oven to 350°F (175°C).

Spread the 1 1/4 cups all-purpose flour in an even layer on a large baking sheet. Bake for 5 to 10 minutes to heat-treat the flour. Remove from oven and let the flour cool completely before using.

Line an 8-by-8-inch baking pan with aluminum foil, leaving an overhang for lifting the bars out later. Spray the foil lightly with cooking spray. Set the pan aside.

In a large mixing bowl, combine 1/2 cup softened unsalted (or vegan) butter, 3/4 cup packed light brown sugar, and 1 tablespoon vanilla extract. Whisk or beat with an electric mixer until the mixture is soft and fluffy, about 3 minutes, scraping down the sides of the bowl as needed.

Add the cooled, baked flour and a pinch of salt (optional, to taste) to the butter-sugar mixture. Stir until fully combined and no dry streaks of flour remain.

Stir in 1 1/2 cups semi-sweet chocolate chips or chunks, reserving 2 tablespoons of the chips to press into the top of the bars.

Turn the dough into the prepared 8-by-8 pan. Use a spatula or clean hands to press the dough down firmly and evenly to the edges and into a smooth, even layer.

Evenly press the reserved 2 tablespoons of chocolate chips into the surface of the dough for a decorative top.

Refrigerate or freeze the pan for at least 2 hours to firm the bars, or chill overnight for best results.

To serve, lift the bars from the pan using the foil overhang and cut into bars. If the bars are frozen, let them sit at room temperature about 10 minutes before slicing for easier cutting.

Optionally drizzle with 10-Minute Homemade Hot Fudge, vegan hot fudge, chocolate syrup, or Salted Caramel Sauce before serving.

Store the bars airtight in the refrigerator for up to 3 weeks or in the freezer for up to 4 months.