Preheat the oven to 350 degrees F. In a medium bowl, mix the flour, brown sugar, granulated sugar, cinnamon, nutmeg and salt using a fork or pastry cutter. Cut the butter into small pieces and gradually add to flour mixture until evenly mixed. Slice the peaches 1/2-inch thick into a bowl. Add the zest from the lemon half. Squeeze juice from the lemon half and stir in with the peaches and zest. Add 2 tablespoons of the maple syrup to the peaches and stir well. Pour the peach mixture into a small pan (8 or 9-inch square) and cover evenly with the crumb topping. Cover with foil and bake for 15 minutes. Remove the foil and bake until crisp and brown on top, an additional 20 to 30 minutes. For the maple cream sauce, pour the heavy cream into a saucepan. Add the remaining 5 tablespoons maple syrup and corn syrup and stir over moderate heat until thickened and reduced by about one-third, about 15 minutes. Refrigerate the sauce until it is cold and thick. Or, if you're in a hurry, set the saucepan into a small bowl of ice (the ice will melt and turn into ice water). Stirring your mixture, it will cool and thicken in about 15 minutes. Drizzle the maple cream sauce over the peach crisp. Serve warm.