Melt butter: Melt butter in small pan or microwave. If browning, cook until golden with brown specks and nutty aroma. Pour into bowl and cool 15-20 minutes.
Mix wet: In large bowl, whisk melted butter, brown sugar, and granulated sugar until combined. Add egg and vanilla. Whisk vigorously 1 minute until smooth and glossy.
Add dry: Add flour, baking soda, and salt to bowl. Stir with spatula until no dry flour remains. Do not overmix.
Add chips: Fold in mini chocolate chips until evenly distributed.
Pipe: Spoon dough into piping bag or freezer bag. Snip tip to create 1.5 cm opening. Pipe small dots (2 cm wide) onto parchment-lined tray.
Chill: Place tray in refrigerator for 1 hour. Uncovered is fine.
Preheat and prep: When ready to bake, preheat oven to 175°C (350°F). Line baking sheet with parchment.
Bake: Transfer chilled dough dots to prepared sheet, spacing 3 cm apart. Bake 9-11 minutes until edges lightly golden, centers still soft.
Cool: Let cookies rest on baking sheet 5 minutes. Transfer to wire rack to cool completely.