1Heat oven to 350ºF. Butter spingform pan, 9x3 inches, or 9-inch square pan. Mix 1 1/2 cups flour and the brown sugar in medium bowl. Cut in butter, using pastry blender or crisscrossing 2 knives, until crumbly. Reserve 1/2 cup mixture for topping. Press remaining mixture on bottom and 1 1/2 inches up side of pan. Bake 15 minutes or until golden brown and set.
2Beat eggs with electric mixer on high speed 1 minute until lemon colored. Beat in sugar, 2 tablespoons flour, the salt and half-and-half. Sprinkle rhubarb over warm crust. Pour egg mixture over rhubarb. Add hazelnuts to reserved crumbly mixture; sprinkle over top.
3Bake 40 to 45 minutes or until set and knife inserted in center comes out clean. Cool at least 2 hours before serving. Run metal spatula along side of tart to loosen; remove side of pan. Store covered in refrigerator.