Crust
Place flour and salt in bowl of a food processor and pulse until combined. Add butter and pulse until mixture resembles coarse crumbs. 

Add water a couple tablespoons at a time, and pulse just until dough comes together (be careful not to overmix). Divide dough 2/3 and 1/3 and pat each ball of dough into a rectangle and wrap in plastic wrap. 

Chill at least 1 hour.

Filling

Preheat oven to 190°c.

On a large sheet of baking paper at least 18 inches long, roll out larger piece of dough to a 16- by 11-inch rectangle. Using parchment paper to transfer, fit dough into a 15- by 10-inch rimmed baking sheet and fold dough overhang under around edge of pan. Keep chilled until ready to fill.

Mix pecans, oats, brown sugar, cinnamon and salt together in a large bowl. Add butter and work into dry ingredients with fingers until mixture is crumbly.

Stir together raspberries, sugar and cornstarch in a large bowl until evenly blended. Break apart pecan mixture and sprinkle onto dough in pan in an even layer. Top with raspberry mixture, spreading to a single layer. Return to refrigerator to keep cool.

On a lightly floured surface, roll out remaining piece of dough to a rectangle 13-inch by 11-inch. Cut 1/2-inch wide zig zag pattern to make 5 strips. Carefully place each strip over raspberry filling in pan and pinch at edges to secure to dough. Brush zig zags and edges with beaten egg.

Bake about 50 minutes or until crust is golden brown and filling is bubbling. Let cool at least 1 hour or completely on wire rack before serving. Use edges of parchment paper to transfer cooled pie to a cutting board to cut into pieces.