Preheat oven to 400 degrees F. Line a very large baking sheet with parchment paper or foil. In a large bowl combine the first five ingredients (through salt). Using a pastry blender, cut in cold butter until mixture resembles coarse crumbs. Stir in the 1 cup finely chopped apple. Make a well in center of flour mixture.
In a small bowl combine the 2 eggs and 3/4 cup heavy cream. Using a fork, stir egg mixture into flour mixture just until moistened. Turn dough out onto a floured surface. Knead dough by folding and gently pressing it for 10 to 12 strokes or until nearly smooth. Divide in half. Pat or lightly roll each half into a 6-inch circle. Cut each circle into 6 wedges. Place wedges on prepared baking sheet.
In a small bowl combine the egg yolk and 1 Tbsp. heavy cream. Brush some of the yolk mixture over wedges. Arrange apple slices on top of wedges, pressing lightly to adhere. Brush with remaining yolk mixture; sprinkle with coarse sugar.
Bake 15 to 18 minutes or until light brown. Cool on baking sheet 5 minutes. Remove and serve warm with Spiced Maple Butter.
Spiced Maple Butter
In a small bowl stir together the butter, maple syrup, and apple pie spice until smooth. Cover and chill for up to 1 week. Serve at room temperature. Makes 2/3 cup.