Cut out the core of each head of Bibb lettuce with a small paring knife so that the leaves will easily pull apart. Skin each peach and slice into thin wedges.
Place 1 head of Bibb lettuce on each of 4 chilled plates. Arrange the wedges of peaches in between the lettuce leaves. Drizzle about 1/4 cup blue cheese dressing on each head of lettuce and sprinkle with a handful of spiced pecans. Serve immediately.
Combine the blue cheese and heavy cream in a 12-inch sautee pan and gently heat over a low flame, stirring with a wooden spoon until the cheese melts and combines with the heavy cream. Take off the heat and let cool for about 10 minutes. Transfer to a bowl and gently fold in the mayonnaise, mustard, creme fraiche, lemon juice and sherry vinegar.
Add a pinch each of salt and pepper. Let chill in the refrigerator for 30 minutes.
Heat the butter in a large sautee pan until foamy. Add the pecans and sugar and toss to coat. Add the spice mix and shake the pan until all the pecans are thoroughly coated with the spice mix. Cook for about 10 minutes or until the butter has been absorbed and the pecans are roasted, continuing to shake the pan. Drain on a paper towel and let cool. This will make more than you need for the recipe; store the remaining pecans in an airtight container.