Preheat your oven to 350 degrees Fahrenheit.
Halve your yellow bell peppers lengthwise and remove the seeds and inner membrane.
Blanch the halved bell peppers in boiling water for about 5 minutes, then drain and set aside.
Melt 3 tablespoons of unsalted butter in a skillet over medium heat and sauté the chopped shallots until soft.
Sprinkle in 1/4 cup of unbleached all-purpose flour and cook until bubbly.
Remove the skillet from heat and add 1 cup of cream cheese, stirring until melted.
Incorporate 1 teaspoon of fresh lemon juice, 1 teaspoon of Dijon mustard, and 2 tablespoons of flat-leaf parsley.
In a separate frying pan, melt 1 tablespoon of unsalted butter and sauté 1 pound of fresh prawns until pink.
Add another teaspoon of lemon juice and cook for another minute.
Mix the sautéed prawns into the cream cheese mixture and season with salt and pepper.
Spoon the filling into the halved bell peppers and sprinkle with 1/2 cup of shredded Monterey jack cheese.
Bake for 30 minutes or until the cheese is bubbly and golden.
Allow to cool slightly before serving.