Bring a large pot of water to boil, and add the potatoes. Cook until fork-tender. Drain and rinse with cold water, then add the butter, gorgonzola, and cream. Blend until smooth, add salt to taste.
While the potatoes are cooking, heat the olive oil in a large cast-iron skillet over medium-low heat.
When hot, add the onion and garlic, and cook for about 3 minutes.
Next, add the carrots and beef. Cook until the beef is fully browned.
Add the tomato paste, rosemary, and worcestershire sauce and stir to combine.
Add the stock, and simmer for about 10 minutes, or until the juices have thickened.
Add the frozen peas and 1 tsp salt, stir to combine.
Spread the prepared mashed potatoes over the beef and vegetable mixture, making an uneven surface on top. Cook at 375 F until golden, about 30 minutes.
Recipe by The Kitchen Paper at http://c02.ddd.mwp.accessdomain.com/gorgonzola-shepherds-pie/