Preheat oven to 350. Prepare a 9x13 baking dish by coating inside bottom with cooking spray.
Add cake mix, milk, oil, eggs, cinnamon and cayenne to a medium-sized bowl. Use a hand mixer to beat for 2 minutes or until combined well. Pour into prepared dish. Bake for 30-35 minutes or until toothpick inserted comes out clean.
While cake is cooling make the tres leches by whisking sweetened condensed milk, evaporated milk, heavy cream and cocoa powder until combined well.
Once cake is warm to the touch, use a fork to generously poke holes all over the top. Pour milk mixture evenly over the top. Cover with plastic wrap and refrigerate for at least 3 hours or up to 12.
Once ready to serve, make the whipped topping by whipping the cream with a stand or hand mixer until soft peaks form. Add sugar, vanilla, and cinnamon then continue whipping until stiff peaks form. Spread over top of the cake and serve. Garnish with fresh strawberries if desired.