In a large bowl, beat together butter, sugars, and vanilla until well-combined and creamy.
Add egg and mix well.
In another bowl, combine remaining ingredients (except chips).
Add dry ingredients to wet ingredients until just combined.
Mix in mini chocolate chips and refrigerate cookie dough for 30 minutes.
Position oven rack in center of oven and preheat to 350°F. Line a large baking sheet with parchment paper. Drop cookies by rounded tablespoons onto prepared cookie sheet, spacing at least 1 1/2 inches apart. Bake for 8 to 12 minutes or until set and light golden brown. Allow to cool on baking sheet for 5 minutes before removing to a rack and cooling completely. Store in an airtight container.
Add a 1/4 cup more flour for cakier cookies. Add a little milk if dough it too dry.