Raspberry Rhubarb pie bars

I got these from Taste of Home and I thought they were yummy.  They're kind of a take on the apple pie bars that Nathan loves and they make a lot (2 dozen) cause they're made in a large jellyroll pan.



3 1/4 c. flour
1 tsp. salt
1 c. butter
3/4 c. plus 1 to 2 Tblsp. 2% milk
1 egg yolk
2 c. sugar
1/3 c. cornstarch
butter (to dot over the top - the more the better I always say)
5 c. fresh or frozen unsweetened raspberries,
   thawed and drained
3 c. sliced fresh or frozen rhubarb, thawed and drained (4 stlks)
Vanilla Icing:
1 1/4 c. powdered sugar
1/2 tsp. vanilla extract
5 to 6 tsp. 2%

In a large bowl, combine flour and salt; cut in butter until crumbly.  Whisk 3/4 c. milk and egg yolk; gradually add to flour mixture, tossing with a fork until dough forms a ball.  Add additional milk, 1 Tblsp. at a time, if necessary.
Divide dough in half so that one portion is slightly larger than the other; wrap each in plastic wrap.  Refrigerate for 1 hour or until easy to handle.
Roll out larger portion of dough between two large sheets of lightly floured waxed paper into an 18-in.x 13-in. rectangle.  Transfer to an ungreased 15-in. x 10-in. x 1-in. baking pan.  Press onto the bottom and up the sides of pan; trim pastry to 1/2 in. above edge of pan.
In a large bowl, combine sugar and cornstarch.  Add raspberries and rhubarb; toss together to coat.  Spoon into pastry and dot with butter.
Roll out remaining dough; place over filling.  Fold bottom pastry over edge of top pastry; seal with a fork.  Prick top with a fork.
Bake at 375 degrees for 45-55 minutes or until golden brown.  Cool completely on  wire rack.
For icing, combine powdered sugar, vanilla and enough milk to achieve a drizzling consistency.  Drizzle over pie (I like to just frost the whole thing).  Cut pie into squares.
(If using frozen rhubarb, measure rhubarb while still frozen, then thaw completely.  Draine in a colander, but do not press liquid out.