Set rack at lowest position in oven and preheat to 350°F. Boil Cognac until reduced to 1/2 cup, about1 1/2 minutes. Cool.
Melt butter in heavy medium skillet over medium heat. Add onion and sauté until soft and translucent but not brown, about 8 minutes. Combine ground pork and chopped bacon in large bowl. Using fork or fingertips, mix together until well blended.
Add sautéed onion, garlic, 2 1/2 teaspoons salt, thyme, allspice, and pepper to bowl with pork mixture and stir until incorporated. Add eggs, cream, and reduced Cognac. Stir until well blended. Using hands, lightly and evenly press meat mixture into a 9x5x3-inch loaf pan. Cover pan tightly with foil. Place pan in 13x9x2-inch baking pan and transfer to oven. Pour boiling water into baking pan to come halfway up sides of loaf pan. Bake pâté until a thermometer inserted through foil into center registers 155-60°F, about 2 to 2.5 hours.
Remove loaf pan from baking pan and transfer to rimmed baking sheet. Place heavy skillet or 2 to 3 heavy cans atop pâté to weigh down. Chill overnight. To serve, place loaf pan with pâté in larger pan of hot water for about 3 minutes. Invert pâté onto platter; discard fat from platter and wipe clean. Cut or spoon pâté onto toast points, top with Strawberry-Rhubarb Jam