Preheat oven to 350 degrees F.
Place a large frying pan over medium high heat. Once it is hot, add the bacon and cook for 2-3 minutes per side, or until fully cooked. Once cooked, drain the bacon on a paper towel to remove any excess fat, but reserve at least one tablespoon of fat in the pan.
Once cooled, chop the bacon into fine pieces and place in a large mixing bowl. Reserve 2 tablespoons of bacon pieces in a separate bowl to use for garnish later.
Next, use a damp paper towel to remove any excess dirt from the mushrooms. Remove the mushrooms stems by gently pulling them out and chop them finely.
Place the mushroom caps on a parchment-lined baking sheet, spaced 2-3 cm apart.
Re-heat the frying pan with the bacon fat over medium-high heat. Add the chopped mushroom stems, shallots, and thyme. Fry for 3-4 minutes, stirring often to fully cook the mushroom stems and shallots, but not brown them. Remove from the heat and add to the large mixing bowl with the bacon pieces. Let the mushroom mixture cool for 5 minutes.
Once slightly cooled, add the cream cheese, ¼ cup of Parmesan cheese, and black pepper and mix everything to combine.
Use a teaspoon to scoop the cream cheese filling into each mushroom cap. Once they are all filled, garnish the top of each mushroom with the remaining Parmesan cheese. Finally, drizzle the olive oil over all the mushrooms.
Place in the oven and bake for 20-25 minutes or until the mushrooms have softened and the filling is starting to turn a light golden brown colour.
Remove from the oven and garnish with the reserved bacon pieces and some extra thyme leaves. Serve immediately and enjoy!