Step 1
Preheat the oven to 375 degrees F (190 degrees C).
Step 2
Pierce the sweet potato several times with a fork and wrap in aluminum foil. Place on a baking sheet.
Step 3
Roast in the preheated oven until sweet potato is fork-tender 70 to 90 minutes. Remove from the oven and let cool enough to handle 5 to 10 minutes.
Step 4
Reduce oven temperature to 350 degrees F (175 degrees C). Lightly grease a 9-inch deep-dish pie plate and place on a rimmed baking sheet to prevent bubbling over.
Step 5
Peel skin off the sweet potato and place flesh into a large bowl. Add butter milk salt pepper sage and nutmeg. Beat using an electric mixer until ingredients are combined. Mix in Cheddar cheese gently. Set aside.
Step 6
Heat vegetable oil in a Dutch oven over medium-high heat. Add mushrooms onion carrots celery and garlic. Sprinkle with salt. Cook until vegetables have softened 5 to 7 minutes. Add venison thyme oregano garlic powder onion powder 1/2 teaspoon salt pepper and sage. Stir to combine breaking up any large pieces of venison. Cook until venison is no longer pink 5 to 7 minutes.
Step 7
Stir flour into the pot and cook for 1 minute. Pour in white wine and stir to loosen any browned bits from the bottom of the pan. Cook until wine has reduced slightly 2 to 3 minutes. Stir in broth. Allow mixture to come to a simmer; continue to cook until filling has thickened 5 to 10 minutes. Stir in peas. Taste and adjust salt and pepper as necessary. Remove from heat and let cool slightly.
Step 8
Pour filling into the prepared pie plate. Top with sweet potato mixture and spread gently across the top covering most of the filling.
Step 9
Bake in the preheated oven until top is set and filling is bubbling about 30 minutes. Allow to cool slightly before serving.