Cover potatoes with water and bring to boil. Salt water and cook potatoes to tender. Drain, return to pot and mash with milk, sour cream, cream cheese, chives, garlic, half the chopped jalapeños or chilies, some pepper and the egg yolk. Cover pan to keep potatoes warm.
Heat oil, 2 turns of the pan, over medium-high heat. Pat meat dry and add to hot pan; brown and crumble then season with salt, pepper, chili powder, cumin and coriander. Stir to toast then add onions, garlic and remaining jalapeños or chilies, Worcestershire and tomato paste. Stir 1-2 minutes then add beer. When beer almost evaporates, add stock and cornmeal and beans, if using, and simmer to thicken over low heat.
Place rack in center of oven and turn on broiler.
Transfer beef chili to a casserole or individual bowls. Using a pastry bag or large food storage bag. pipe the potatoes on top of the chili. Transfer to broiler to brown potatoes. Top with pickled jalapenos and serve.