Preheat the oven: Set your oven to 350°F (175°C) and line a baking sheet with parchment paper.
Mix the dough: In a large bowl, stir together the cake mix, whisked eggs, and melted butter until a thick dough forms.
Scoop and bake: Drop spoonfuls of dough onto the baking sheet, spacing them 2 inches apart. Bake for 7-8 minutes until set but still soft.
Cool the cookies: Let them rest on the baking sheet for 4-5 minutes, then transfer to a wire rack to cool completely.
Make the glaze: In a saucepan over medium-low heat, whisk together butter, sugar, water, and vanilla for 4 minutes until smooth.
Glaze the cookies: Spoon 1 teaspoon of glaze over each cookie, spreading gently if needed. Let it set for a few minutes.
Optional final touch: Dust with powdered sugar for extra sweetness before serving.