Crumble: Add flour, white sugar, brown sugar salt, baking powder to bowl and whisked together well. Then add oats and crushed pecans and mix well. Add the chilled butter cubes and mix with a fork braking up the butter and mixing into the dry ingredients. There will be clumps and pieces and that is okay.  Set aside.

Lemon Creme Anglaise: Heat the milk in a medium saucepan and stir in about half the sugar. Bring to a simmer, then remove the pan from the heat. Combine the yolks in a small bowl with the remaining sugar and whisk until smooth. Add the flour and vanilla and mix until well incorporated (the mixture will be very thick at this stage). Thin with half the warm milk, mix well, then pour the mixture back into the saucepan. Stir constantly over medium heat with a small whisk or a wooden spoon; the mixture will thicken as it cooks. When the custard comes to a boil, stir for a continuous minute, then remove from heat, add the lemon zest, and transfer to a bowl. Cover and refrigerate up to three days. When ready to serve, re-whip the custard to loosen it (it will be very thick). Whip the cream to a soft peak and fold it into the custard, in two or three batches, until well combined.

Pour jar of fruit filling into a 9x9 stoneware baking dish. Sprinkle the crumble mixture over the fruit filling. Bake at 375 for 35 minutes until crumble is golden brown and fruit is bubbly. Pull from oven and let cool a bit before serving with topping.