Preheat oven to 350 degrees. Grease 9" by 9" metal baking pan.
In large bowl, with mixer at low speed, beat butter and sugar until mixed, occasionally scraping bowl with rubber spatula. Increase speed to high; beat until light and fluffy.
With mixer at low speed, beat in egg yolks until well combined, constantly scraping bowl with rubber spatula. Add flour and salt and beat until blended, occasionally scraping bowl. With spoon, stir in walnuts.
With lightly floured hands, pat half of dough evenly into bottom of pan. Spread strawberry preserves over dough. With lightly floured hands, pinch off 3/4-inch pieces from remaining dough and drop over preserves; do not pat down.
Bake 45 to 50 minutes until golden. Cool completely in pan on wire rack. When cool, cut into 3 strips, then cut each strip crosswise into 10 pieces.
Each bar: About 130 calories, 2 g protein, 11 g carbohydrate, 9 g total fat (4 g saturated), 31 mg cholesterol, 70 mg sodium.