Preheat oven to 350°. Spray a 13×9-inch baking pan with baking spray with flour.
In a large bowl, whisk together brown sugar, peanut butter, and oil until smooth and creamy. Whisk in eggs and vanilla until combined.
In a medium bowl, sift together flour, baking powder, baking soda, and salt. Gradually add flour mixture to sugar mixture alternately with buttermilk, beginning and ending with flour mixture, stirring just until combined after each addition. Spread batter into prepared pan.
Bake until a wooden pick inserted in center comes out clean, 35 to 40 minutes. Let cool completely in pan on a wire rack.
Using a fork, poke all over top of cake. Reserve ¼ cup Cola Syrup; brush remaining Cola Syrup all over cake. Top with Creamy Peanut Butter Frosting. Garnish with peanuts, if desired. Serve with reserved syrup.
Recipe by Paula Deen Magazine at https://pauladeenmagazine.com/peanuts-cola-poke-cake/