1. Heat oven to 400 degrees F. Place oven rack in lower third of oven.
2. Combine flour, cinnamon and salt in bowl. Cut in butter with pastry blender until mixture resembles coarse crumbs. Add sugar and walnuts. Stir in whole egg and yolk. Work into large ball; divide dough in half.
3. Coat 15-1/2 x 10-1/2 x 1-inch jelly-roll pan with cooking spray. Press half of dough into pan, up sides .
4. Bake in 400 degree F oven 12 to 15 minutes or until barely colored. Remove from oven.
5. Meanwhile, roll remaining dough between sheets of waxed paper to a 1/4-inch thickness. Put on baking sheet in freezer 15 minutes.
6. Reduce oven temperature to 350 degrees F. Reposition rack in upper third of oven.
7. Spread jam evenly over baked bottom. Remove top piece of waxed paper from chilled dough. Cut 1/2- to 3/4-inch-wide diagonal strips. Arrange strips in lattice pattern on top of jelly, 1/2 to 3/4 inch apart, piecing strips if necessary. Press ends of strips to edge of baked bottom. Place strips around edge of bottom for border.
8. Mix yolk and water. Brush over pastry. Decorate edge with nuts.
9. Bake in 350 degree F oven 35 minutes, until browned. Cool. Dust with sugar. Makes 24 servings.