Combine yeast and 1/4 cup warm water in a 1-cup liquid glass measuring cup; let stand 5 minutes.
Combine milk and next 3 ingredients in a heavy saucepan; heat until shortening melts, stirring occasionally. Cool to 105° to 115°.
Combine yeast mixture and milk mixture in a large mixing bowl; add 1 1/2 cups flour, and beat at medium speed withan electric mixer until blended. Stir in egg until blended. Beat in enough remaining flour to make a soft dough. Place dough in a well-greased bowl, turning to grease top.
Cover and let rise in a warm place (85°), free from drafts, 1 1/2 hours or until doubled in bulk.
Punch dough down, and divide into thirds; roll each portion into a 9-inch circle on a lightly floured surface. Brush with 2 tablespoons butter, and cut into 8 wedges. Roll up each wedge tightly, beginning at wide end. Place, point side down, on a greased baking sheet, and bend into crescent shapes.
Cover and let rise in a warm place, free from drafts, 45 minutes or until doubled in bulk.
Bake at 400° for 8 minutes or just until lightly browned; cool on baking sheets on wire racks. Cover and freeze until firm. Place frozen rolls into heavy-duty zip-top plastic bags; freeze up to 1 month.
Remove crescent rolls from freezer; place on baking sheets,and thaw at room temperature.
Bake at 400° for 5 to 7 minutes or until lightly browned.