In a large skillet, over medium-high heat, cook the sausage, crumbling it with a wooden spoon, until browned, about 5 minutes. Spoon off and discard any fat. Add the tomatoes and their juices. Crush the tomatoes with the back of the spoon. Stir in the tomato paste, parsley, salt, and red pepper flakes and cook until the mixture has thickened slightly, about 5 minutes. Spoon a thin layer of the meat sauce into the bottom of an 8-by-11-inch baking dish or shallow 2-quart casserole. Top with half the eggplant slices, overlapping them slightly, and half the meat sauce. Repeat with the remaining eggplant and meat sauce.
In a small saucepan, over medium-low heat, warm the cream and Feta, stirring frequently, until smooth. Drizzle the cheese mixture over the casserole. Cover with foil and bake for 30 minutes. Uncover and bake until the eggplant is tender and the top is golden, about 30 minutes more.
Warm the pitas in the oven during the last 5 minutes. Sprinkle the casserole with the mint and the additional Feta. Serve with the pitas.
Tip: Lamb sausage gives this dish a Greek accent, but ground beef tastes delicious, too.