Preheat your oven to 350°Fahrenheit. Grease using butter or spray with cooking spray an 8-10 oz oven-safe ramekin. In a small or medium mixing bowl, whisk the melted butter with the brown sugar and white sugar until fully combined.
Add the egg yolk and vanilla extract and whisk to fully combine.
Add the baking soda, salt and flour to the bowl. Stir all of the ingredients together until a cookie dough forms. Mix in 2 tablespoons of sprinkles and press the cookie dough into an 8-10oz ramekin. Add an extra pinch of sprinkls on top if desired.
Bake the single sugar cookie in the preheated oven for 18-24 minutes, depending on how done you want the cookie. A baking time of 16-18 minutes will give you a slightly underdone cookie that's just golden brown around the edges versus 24 minutes of cooking time will give you a fully baked cookie with a more crisp edge. Enjoy!
Notes
Use an oven-safe ramekin that holds 8-10 ounces. If you use any smaller oven-safe dish, then the cookie dough might overflow while baking.
Can I make this for two? Absolutely! Easily double the ingredients and split the cookie dough between 2 ramekins to make two deep dish sugar cookies.
Serve this cookie with a scoop of vanilla ice cream for an extra indulgent dessert!
I haven't tested this single serve cookies recipe other than in a ramekin. However, you could try shaping the dough into a ball to make a big cookie; place on a parchment paper line baking sheet; press the cookie down a bit to flatten slightly and bake at the same temperature as the deep dish cookie, 350F, for 18-22 minutes until the edges just starting turning golden brown.