Heat oven to 325. Line baking sheets with parchment paper. Beat together almond paste, sugar,and 1 egg white in medium-size bowl until smooth. Beat in second egg white, then vanilla extract. Stir in flour until dough forms. Drop batter by teaspoonsful 2 inches apart on prepared sheets. Cover each cookie with pine nuts, about 1/2 teaspoon each. Bake in top third of 325 oven until edges are golden, 15 minutes. Cool cookies on sheet on rack.