Preheat oven to 350 degrees. Line two baking sheets with parchment paper. Arrange provolone slices in a single layer on the baking sheets. You may have to work in batches or can use three baking sheets.

To make the filling: Microwave the cauliflower in a glass bowl for 3 to 5 minutes, until soft. Then purée the cauliflower with either an immersion blender or food processor until smooth. Add 2 tablespoons of butter to the cauliflower while it's still warm so that the butter melts in with the cauliflower. Mix in the salt and pepper.

Stir 1 cup of shredded sharp cheddar into the mashed cauliflower. Then mix in ¼ cup of the chopped green onions. Save the remaining green onions as garnish. Once you've made the filling, you can bake the provolone slices.

To bake and assemble the pierogi: Bake the provolone slices for 3 to 5 minutes until bubbly and slightly browned. Depending on your oven, you may need to bake them for longer. Make sure to watch them closely.

Remove the baked provolone slices from the oven and let cool for 3 to 5 minutes. Once cooled, place about 2 tablespoons of the filling on one half of each slice of provolone. Fold the slice of provolone over the filling and press the edges together to seal. Repeat with the remaining slices of provolone. You may end up with a little bit of extra filling.

Once all the provolone slices are stuffed and the pierogi are formed, turn your oven to broil. Broil the pierogi for 30 seconds to 1 minute until browned. Then remove from the oven and let cool before serving.

While the pierogi are cooling, sauté the shallots in a skillet over medium heat in the remaining 2 tablespoons of butter for about 5 minutes, until soft. Add the remaining green onions to the skillet to just slightly cook them.

To serve, dish up four pierogi per plate and garnish with sautéed shallots and green onions. Enjoy!