Preheat the oven to 350 degrees F. Line two large baking sheets with Silpat baking matsor parchment paper. Set aside.
In a medium bowl, whisk together the oats, flour, baking soda, salt, and cinnamon. Set aside.
2 cups old fashioned oats, 3/4 cup all-purpose flour, 1/2 teaspoon baking soda, 1/2 teaspoon salt, 1/2 teaspoon ground cinnamon
Using a mixer, beat the butter, peanut butter, and sugars together until creamy, this will take about 2 minutes, on medium speed. Beat in the egg and vanilla extract. Mix until well combined.
3/4 cup unsalted butter at room temperature, 3/4 cup creamy peanut butter, 1 cup granulated sugar, 1/2 cup light brown sugar, 1 large egg + 1 yolk, 1 teaspoon vanilla extract
On low, add in the dry ingredients and mix until just until the combined.
Scoop the cookies into round balls (1/4 cup sized) and place on the prepared baking sheets, leaving 2 inches in between cookies. Bake for 10-12 minutes, or until the cookies are lightly browned around the edges, but still soft in the middle.
Remove cookies from oven and let cool on the baking sheet for about 5 minutes. Transfer to a wire rack and cool completely.