Make the mashed potato filling:

1. Place potatoes in a medium pot and cover with salted water to cover potatoes by about an inch. Bring to a boil over high heat.
2. Reduce heat to low, cover, and simmer for 15-20 minutes, or until potatoes fork tender (soft when you insert a fork).
3. Drain potatoes and place back in the pot. Use a potato masher (or a fork) to mash the potatoes until mostly smooth.
4. Add butter and use an electric hand mixer to whip until melted and incorporated.
5. Slowly add in the cream while mixing until smooth and creamy
6. Add cheddar cheese, sour cream (if using), garlic powder, onion powder, salt, pepper, and green onions (if using). Mix until combined and smooth. Remove from heat and allow filling to cool completely before assembling.

Assemble the spring rolls:

1. Place a spring roll wrapper diagonally on a clean surface. Add about 1½ tablespoons filling in the centre, about ¾ of the way down from the top. Don't overfill or they may burst.
2. Fold bottom corner over filling. (The bottom corner should approximately touch the centre of the wrapper).
3. Fold in both side corners to the center and fold over top.
4. Roll tightly upward, leaving about 2 inches at the top.
5. Lightly brush top corner with water and roll up to seal like a burrito. Place finished rolls on a parchment lined baking sheet and freeze for at least 30 minutes (or up to overnight).

Bake and serve:

1. Preheat oven to 425°F.  Mix vegetable oil and melted butter together.
2. Brush or spray spring rolls generously on all sides. Place in oven and bake for 15 minutes. Flip spring rolls and bake another 12-15 minutes, until golden and crispy.
3. Remove from oven and top with sour cream, cheddar cheese, bacon bits, and green onions. Serve warm.