Set rack at lowest position in oven and preheat to 350°F Boil Cognac until reduced to 1/2 cup, about 1 1/2 minutes. Cool.
Melt butter in heavy medium skillet over medium heat. Add onion and saute 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 sauteed 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.
Line 9x5x3-inch metal loaf pan with bacon slices, arranging 8 slices across width of pan and 3 slices on each short side of pan and overlapping pan on all sides. Using hands, lightly and evenly press half of meat mixture (about 3 1/4 cups) onto bottom of pan atop bacon slices. Arrange ham strips over in single layer. Top with remaining meat mixture.
Fold bacon slices over, covering pate. Cover pan tightly with foil. Place pan in 13x9x2-inch metal baking pan and transfer to oven. Pour boiling water into baking pan to come halfway up sides of loaf pan. Bake pate until a thermometer inserted through foil into center registers 155°F, about 2 hours 15 minutes.
Remove loaf pan from baking pan and transfer to rimmed baking sheet. Place heavy skillet or 2 to 3 heavy cans atop pate to weigh down. Chill overnight. DO AHEAD Can be made 4 days ahead.
Place loaf pan with pate in larger pan of hot water for about 3 minutes. Invert pâté onto platter; discard fat from platter and wipe clean. Cut pate crosswise into 1/2-inch slices.