Preheat the oven to 350°F (175°C). Spray a 10-cup bundt pan with non-stick cooking spray and set aside.
Open both cans of biscuits and cut each biscuit into quarters. Place the biscuit pieces into a large bowl or a zip-top bag.
In a small bowl, combine the granulated sugar and ground cinnamon. Sprinkle this cinnamon-sugar over the biscuit pieces and toss or shake until evenly coated.
Sprinkle 1/4 cup of the chopped walnuts in the bottom of the prepared bundt pan. Add half of the coated biscuit pieces on top. Sprinkle the remaining 1/4 cup walnuts over the biscuit layer, then add the remaining biscuit pieces.
In a liquid measuring cup, whisk together the melted butter, packed brown sugar, heavy cream, and salt until a thick, grainy sauce forms.
Pour the brown sugar sauce evenly over the arranged biscuit pieces in the bundt pan.
Bake uncovered for 30–40 minutes, or until the dough pieces are cooked through and the top is golden and set.
Allow the monkey bread to cool in the pan for 5–10 minutes, then invert onto a serving platter. Replace any pieces or nuts that stick to the pan back onto the bread. Serve warm.