Whisk yolks and sugar in bowl to blend. Pour cream into heavy medium saucepan. Scrape seeds from vanilla bean into cream; add bean. Bring to boil. Gradually whisk hot cream into yolk mixture. Return to saucepan; stir over low heat until mixture thickens and leaves path on back of spoon when finger is drawn across, about 4 minutes; do not boil. Remove from heat; stir in amaretto. Transfer to bowl. Press plastic wrap directly onto surface of cream to prevent skin from forming. Chill until cold. (Can be made 4 days ahead. Keep chilled.) Remove vanilla bean.
Melt butter in large skillet over medium heat. Add apricots and 1/4 cup sugar. Scrape in seeds from vanilla bean; add bean. Cook until apricots are tender, fall apart and form thick puree, stirring occasionally, about 15 minutes for canned apricots and 30 minutes for fresh. Cool. Remove vanilla bean. Sweeten mixture with more sugar, if desired.
Preheat oven to 425°F Roll out pastry on floured surface to 12x16-inch rectangle. Cut in half lengthwise, forming two 6x16-inch rectangles. Place 1 rectangle in center of baking sheet. Spread apricots evenly over pastry, leaving 3/4-inch bortder on all sides. Brush border with egg glaze. Place second rectangle atop filling. Press edges firmly to seal. Brush with glaze. To form rim, fold up 1/2 inch of edge all around; press to seal. Brush top with glaze; sprinkle with sugar. Using small sharp knife, make diagonal cuts 2 inches apart across tart, cutting just to filling. Bake until golden about 25 minutes. Cool. Serve with amaretto cream.