Preheat oven to 375°F. Beat butter and brown sugar in large bowl with electric mixer on medium speed until light and fluffy. Add flour, oats and salt. Press into ungreased 13X9-inch baking pan. Bake 20 minutes or until golden; cool.

Meanwhile, combine 1/4 cup water, pudding mix, sugar and egg yolks in medium saucepan . Stir in remaining 1-1/2 cups water and lemon juice. Bring mixture to a boil, stirring constantly. Mixture will thicken. Cut remaining 2 tablespoons butter into small pieces. Remove pudding mixture from heat and stir in butter. Cool slightly; pour over crust. Chill at least 4 hours. Sprinkle with powdered sugar just before serving. Cut into bars.