Heat oven to 375°F. In medium bowl, mix butter, brown sugar and vanilla with spoon. Stir in 2 cups flour, the oats, nuts, baking soda and salt until crumbly (we needed to add more oats and flour, probably another cup of each. We also used our hands to mix this). Reserve 2 cups crumbly mixture. Press remaining crumbly mixture in ungreased 15x10x1-inch pan.

In large bowl, mix granulated sugar, 2/3 cup flour, the milk and eggs with spoon until smooth. Fold in strawberries and rhubarb. Spoon filling onto crust. Sprinkle with reserved crumbly mixture.

Bake 40 to 50 minutes or until topping is golden brown and filling is set. Cool slightly, about 30 minutes. For serving pieces, cut into 5 rows by 4 rows. Serve with whipped cream. Store covered in refrigerator.