Preheat the oven to 350°F (175°C).
Melt 2 teaspoons butter and pour it over 1/4 cup breadcrumbs in a bowl; stir until evenly coated.
Spread the buttered breadcrumbs on a baking sheet and toast in the preheated oven 6–8 minutes, or until golden brown; transfer toasted breadcrumbs to a small dish and set aside.
Cook the jumbo pasta shells according to package directions until al dente, drain, and let cool enough to handle.
Meanwhile, heat the marinara sauce in a medium pot over medium-low heat until warm; keep covered and on low heat.
Make the ricotta filling: in a mixing bowl, whisk the egg, then add 2 cups ricotta and 1 cup Italian blend shredded cheese; stir until smooth and combined.
Prepare the Alfredo-style cream: combine 3 ounces butter and 4 ounces heavy cream in a small pot over medium-high heat; when it begins to bubble, stir in 3 ounces shredded Parmesan until melted, then reduce heat to low and simmer briefly to thicken.
Stuff each cooked shell with the ricotta mixture until you have 15 filled shells.
Divide 24 ounces marinara among three oven-safe bowls or pie plates, pouring about 1 cup sauce into each dish.
Place 5 stuffed shells on top of the sauce in each bowl, then pour enough of the Alfredo-style cream over the shells to partially cover them.
Bake the bowls in the oven until heated through, about 20 minutes.
Remove from the oven and garnish with the toasted breadcrumbs and 2 teaspoons chopped fresh parsley before serving.
