Preheat oven to 325 degrees. Line an 8x8" or 9x9" pan with parchment paper, set aside.

Place butter, cocoa and sugar in a large microwave-safe bowl and microwave for about 1 minute and 30 seconds, or until butter is melted. Mix everything together until smooth. Add in eggs and vanilla and mix until smooth. Pour in the flour and mix until completely combined. The batter will be very thick. Pour batter in prepared pan and spread into an even layer. Bake for 20 minutes. They will NOT look done but will be going back into the oven. Allow brownies to cool in pan for 20 minutes or until warm to the touch, not hot. During this time, prepare pumpkin pie layer and preheat oven to 425 degrees.

In a large bowl, beat both sugars and egg until combined. Stir in pumpkin puree and spices until smooth. Pour in evaporated milk and mix until completely combined. Pour mixture over slightly cooled brownies and spread into an even layer. Place pan into 425 degree oven. After 15 minutes, turn oven down to 350 degrees and bake for 22-25 minutes or until top is set. (If it's a tiny bit wiggly, that's okay.) Allow bars to cool completely in pan at room temperature for about 2 hours and then place covered in refrigerator for at least 30 minutes before serving so they're not too soft.

Pumpkin pie brownies will stay fresh for up 5 days stored covered or in an airtight container in the refrigerator.