‘Cold-weather favorite’: Just 4 ingredients. This is one I can make on autopilot.

Because this recipe is so streamlined, it’s an easy canvas for small tweaks. If your hot cocoa mix is very sweet, you can replace 2–3 tablespoons of it with unsweetened cocoa powder to deepen the chocolate flavor without adding more sugar. For a marshmallow-topped version, scatter a handful of mini marshmallows over the surface during the last 5 minutes of baking; they’ll puff and toast slightly, mimicking the top of a mug of hot chocolate. If you like a bit of texture, fold in 1/3 to 1/2 cup of chocolate chips, chopped chocolate, or toasted nuts (pecans or walnuts work nicely) before spreading the batter into the pan. To introduce a subtle spice note, whisk 1/4 teaspoon ground cinnamon or a pinch of cayenne into the dry ingredients—both nod to older, spiced drinking chocolate traditions. For a dairy-free variation, use a dairy-free hot cocoa mix, substitute melted coconut oil or a neutral vegetable oil for the butter, and confirm your cocoa mix is compatible with your dietary needs. Finally, if you prefer a more cake-like brownie, add 1 extra egg and bake a few minutes longer; for extra fudgy results, err on the shorter end of the baking time and chill the cooled brownies briefly before slicing for cleaner, denser squares.