Preheat your oven to 350°F (175°C). In a medium saucepan, combine chocolate and butter over low heat, stirring until melted and smooth. Allow to cool slightly.

Add sugar and eggs to the chocolate mixture, whisking vigorously until blended. Incorporate eggs one at a time. The mixture should be glossy.

Fold in the flour gently with a spatula, creating a cohesive, thick batter. Stop mixing as soon as no dry flour remains.

Line an 8x8-inch baking pan with parchment paper. Pour brownie batter into the pan, spreading evenly and smoothing the top.

Bake for 25–30 minutes until edges are firm and a toothpick comes out with moist crumbs.

Allow brownies to cool in the pan on a wire rack for 10–15 minutes. Lift them out using the parchment paper and decorate with sprinkles or candy eyes.

Slice fully cooled brownies into squares or shapes, transfer to a serving platter, and optionally top with whipped cream or more sprinkles.