- 1 cup butter
- 1/2 cup white sugar
- 1/2 cup brown sugar
- 2 eggs
- 1 egg yolk
- 2 teaspoons vanilla extract
- 1 teaspoon vanilla butter and nut flavoring
- 3 cups all-purpose flour
- 1 cup old-fashioned oats
- 1 teaspoon baking powder
- 1 teaspoon baking soda
- 1/2 teaspoon salt
- 1/4 teaspoon ground cinnamon
- 2 cups white chocolate chips
- 1 cup finely chopped rhubarb
- 1 cup chopped pecans
- Preheat oven to 350 degrees F (175 degrees C). Line 2 baking sheets with parchment paper.
- Combine butter, white sugar, and brown sugar in a bowl; beat with an electric mixer until fluffy. Mix in eggs, egg yolk, vanilla extract, and vanilla butter and nut flavoring. Add flour, oats, baking powder, baking soda, salt, and cinnamon; mix until dough is blended.
- Fold white chocolate chips, rhubarb, and pecans into the dough. Drop dough onto the baking sheets using a 1 1/2-inch cookie scoop.
- Bake in the preheated oven until bottoms are browned and edges are firm, 18 to 20 minutes. Cool on the baking sheets for 5 minutes. Transfer to a wire rack to cool.