Step 1: Preheat your oven to 425°F (220°C).
Step 2: In a large mixing bowl, whisk together the pumpkin puree, sweetened condensed milk, and eggs until smooth and thoroughly combined.
Step 3: In a separate small bowl, combine the cinnamon, ginger, nutmeg, cloves, salt, and brown sugar (if using). Add this spice mixture to the pumpkin mixture, mixing until just blended. Do not overmix.
Step 4: Pour the pumpkin filling into the unbaked deep-dish pie crust. You may place the pie on a baking sheet for easier handling and to catch any potential drips.
Step 5: Bake for 15 minutes at 425°F (220°C).
Step 6: Reduce the oven temperature to 350°F (175°C) and continue baking for an additional 35-45 minutes, or until a knife inserted near the center comes out clean. The center may jiggle slightly, which is normal.
Step 7: Carefully remove the pie from the oven and let it cool completely on a wire rack for at least 2-3 hours. This is crucial for the custard to set properly.
Step 8: Once cooled, refrigerate the pumpkin pie for at least 4 hours, or ideally overnight, before slicing and serving. Serve chilled with whipped cream or your favorite topping.