2 1/2 sticks unsalted butter (10 ounces), at room temperature
1 cup light brown sugar
1/2 cup granulated sugar
1 large egg, at room temperature
1 large egg yolk, at room temperature
1 tablespoon pure vanilla extract
1 1/2 cups semisweet or white chocolate chips
1 1/2 cups dried cranberries
Preheat the oven to 325°. Line 2 baking sheets with parchment paper.
In a medium bowl, mix the flour with the oats, baking powder, baking soda and salt. In a standing mixer fitted with the paddle, beat the butter and both sugars at medium speed until creamy. Add the egg followed by the egg yolk and vanilla, beating well between additions and scraping down the side of the bowl as necessary. Beat in the dry ingredients, then add the chocolate chips and cranberries and beat until incorporated.
Spoon heaping teaspoons of the dough onto the baking sheets, 2 inches apart. Bake for 12 to 15 minutes, until the cookies begin to brown at the edges. Let the cookies cool on the baking sheets, then transfer them to a rack to cool completely.
The cookies can be stored in an airtight container for up to 4 days.