wild Ophelia's triple berry pie

Directions

1. Prepare crust: in large food processor, pulse walnuts until coarsely chopped. Place chopped into a separate bowl.
2. Process both flours, espresso powder, and sugar; just to combine. Add cold butter cubes and pulse until butter bits are the size of oatmeal & peas (don't pulse too much, the butter chunks should not be uniform). Add chopped walnuts and pulse briefly about 2-3 times. Add 1 Tablespoon of cold cream and pulse a few times. Slowly add another Tablespoon whilst pulsing. The dough should hold together when pinched but you should still be able to see butter bits. If the dough isn't coming holding together, slowly add remaining cream; you probably won't need all 3 Tablespoons.
3. Divide dough into two equal parts. Form each one into a disc, wrap with cling wrap and refrigerate for at least five hours or overnight.{Note: well-wrapped, the dough can be refrigerated for about 5 days.}
4. Flour a large work surface. Remove one disc from refrigerator and, using a lightly floured rolling pin, roll disc into a 12" circle. Carefully transfer to a 9" pie plate, trimming the overhang and crimping edges as desired. {My dough broke apart as it was rolled out; if this happens, gently press it back together once it's in the pan.} Refrigerate crust as you roll out second disc.
5. Have a flat, parchment paper lined sheet on hand. Repeat rolling process with second dough disc. You can either stamp out various shapes using cookie cutters or, if you're feeling ambitious, go ahead and roll out the second dough into another 12" circle. Place cut outs (or crust) onto parchment lined sheet and chill whilst filling is prepared.
6. Preheat oven to 375 F.
7. Prepare filling: in a large bowl, mix everything together using a large wooden spoon or rubber spatula. Once combined, gently bruise and crush the berries. Don't go overboard, there should be a healthy mix of whole, half and crushed berries (try not to mush things up too much).
8. Remove dough-lined pie plate from refrigerator. Pour filling into the crust and try to even out the surface as much as possible. Remove dough cut-outs and place them on top of filling (keep in mind that they will expand while baking). Brush crust edges & cut outs with beaten egg and sprinkle with 1 Tablespoon of granulated sugar. {Note: if you made a solid top crust, be sure the cut about four 2" slits around the center.}
9. Place pie in oven and bake 45-60 minutes, or until filling starts to bubble and crust turns an even deeper golden brown. If the filling starts to spill over, place a foil lined pan on the rack below the pie.
10. Remove pie from oven and place onto cooling rack. Cool completely before serving.