Preheat the oven to 350°F. Line a 9x13-inch metal baking dish with high-quality parchment paper, leaving an overhang on two sides to act as handles. Press the paper firmly into the corners and coat lightly with vegetable oil spray.

In a large ceramic or glass mixing bowl, vigorously whisk the neutral oil, granulated sugar, large eggs, and pure vanilla extract until the mixture is completely smooth, pale, and fully emulsified.

Add the unsweetened cocoa powder, all-purpose flour, ground cinnamon, chili powder, kosher salt, and baking powder directly into the wet emulsion.

Using a wooden spoon or silicone spatula, stir the ingredients firmly until a thick, glossy, dark batter forms and no dry streaks of flour remain.

Gently fold the semi-sweet chocolate chips into the batter, ensuring they are evenly distributed throughout the dense matrix.

Pour the heavy batter into the prepared baking pan, using an offset spatula to smooth it evenly into the corners.

Bake in the preheated 350°F oven for 20 to 25 minutes. The brownies are finished when the top develops a shiny, crinkled crust and a wooden tester inserted into the absolute center emerges with dense, fudgy crumbs (not wet batter).

Do not slice the brownies immediately. Allow them to cool completely in the pan on a wire rack. This critical thermal resting phase allows the dense crumb and molten chocolate chips to structurally set.

Once fully cooled, use the parchment paper overhang to lift the entire block of brownies out of the pan. Slice cleanly into 16 uniform bars with a sharp chef's knife before serving.