Preheat oven to 375°F (190°C). Grease a pie plate, casserole dish or square pan with butter.
In a large bowl, whisk together the sugar, cornstarch, grated ginger, orange zest, juice and vanilla.
Add peaches and blueberries, stir to coat and pour into a pie plate or casserole dish. Set aside.
Make crisp topping by mixing oats with the ground seeds, flour, sugar, spices, orange zest and salt. Grate in the cold butter and mix with hands until crumbly. If not baking immediately, place topping in the fridge to keep cold, otherwise sprinkle crisp topping overtop the fruit. Place the crisp on a baking sheet to catch any over-flowing bubbling molten fruit. Bake in a preheated oven for 25 minutes. Remove, sprinkle pecans over-top and bake again for an additional 5–10 minutes or until fruit is bubbling and topping is golden. If topping seems to be getting too brown before fruit is bubbling, loosely tent with foil.
Rest on a cooling rack for at least 20 minutes before serving. Serve warm or cold.