Step 1

In a medium saucepan, melt the butter over medium heat until melted. Remove from the heat.

Step 2

Add the dark brown sugar and granulated sugar and stir until sugars are incorporated and smooth. Chill the mixture for 10 minutes.

Step 3

Remove from the refrigerator and stir in the egg, egg yolk, and vanilla.

Step 4

Add the flour, oats, baking soda, 1/2 teaspoon salt, and cinnamon and mix together.

Step 5

Stir in the white chocolate chips and chocolate chips.

Step 6

Roll by hand into 24 medium-size balls or use a scoop, and place on a light-colored cookie sheet.

Step 7

Chill for 30 minutes.

Step 8

Preheat the oven to 325 degrees F. Remove the cookies from the refrigerator and bake for 12 to 14 minutes.