Preheat oven to 350 degrees F. Line a 9×13 pan with parchment paper and lightly spray with nonstick cooking spray. Set aside.
Brownies: Add butter, sugar and cocoa powder to stand or hand mixer and beat at medium speed for 2 minutes. Add eggs to the batter one at a time, beating after each addition just until incorporated. Beat in vanilla.
In a separate bowl, mix together flour, baking powder, salt and cinnamon then beat into batter just until combined. Add 1 cup semi-sweet chocolate chips and 3/4 cups chopped pecans to batter and stir until just combined. Pour batter evenly into pan.
Bake at 350 degrees for 30-35 minutes. Let pan cool on a wire rack for 5 minutes then poke holes all over with the back of a wooden spoon. Pour 1/2 cup caramel over brownies and spread into holes with a spatula. Refrigerate brownies for one hour or freeze for 30 minutes to let the caramel set. Meanwhile, prepare the Chocolate Frosting.
Chocolate Frosting: Beat butter, cocoa, corn syrup and vanilla in small bowl until blended. Add powdered sugar and 2 tablespoons milk and beat until smooth, adding additional milk if needed to reach spreading consistency.
Once caramel has set, frost brownies with Chocolate Frosting (you don't have to use all of it but I highly recommend it!). Sprinkle evenly with 1/2 cup chopped pecans, 1/4 cup mini chocolate chips and drizzle with 1/4 cup caramel.
You can serve immediately or refrigerate to allow frosting to set and make cutting easier. I LOVE to microwave my brownie serving for 15 seconds or so before devouring.