In a small bowl, use the back of a spoon to cream the butter and sugar together until light colored and smooth.
Add vanilla extract, milk, and sea salt and stir to mix thoroughly.
Add flour and mix well, until fully incorporated.
Fold in sprinkles, if using.
Serve immediately in two small bowls or refrigerate for 3-4 days. Allow cookie dough to come up to room temperature before enjoying from the fridge.
Notes
*This recipe is egg-free and is safe to eat raw as long as the flour has been properly heat-treated.**To heat-treat flour: Place the flour in a microwave-safe bowl and heat it on high in 30-second intervals, stirring between each interval, until the flour reaches 165°F. This usually takes about 1 to 2 minutes.OR: Spread the flour on a baking sheet and bake at 350°F (175°C) for 5-7 minutes. The internal temperature should reach at least 165°F to kill any potential bacteria. Let the flour cool completely before adding it to the cookie dough.