In a large bowl, beat butter, brown sugar, and granulated sugar until smooth and creamy.
Add milk and vanilla. Mix until combined.
Add heat-treated flour and salt. Mix until a soft dough forms.
Fold in sprinkles (and white chocolate chips if using).
Adjust texture:
Add 1 tsp milk if too thick
Add 1 tbsp flour if too soft
Chill for 15–20 minutes if you want a thicker scoopable texture, or eat immediately.