In a mixing bowl, combine all-purpose flour, wheat flour, sugar, and salt. Cut in cold, cubed butter until the mixture resembles coarse crumbs. In a separate bowl, whisk together an egg yolk and cold milk, then gradually add to the flour mixture. Mix just until combined; avoid overmixing. Form the dough into a disk, wrap in plastic, and refrigerate for at least 1 hour.

Preheat your oven to 375°F while you prepare the rhubarb. In a bowl, toss the chopped fresh rhubarb with sugar, vanilla paste, cardamom, and ginger until well coated. Spread the mixture on a lined baking sheet, then cover with foil. Roast for 20 minutes, then remove the foil and bake for an additional 5-10 minutes, until the rhubarb is tender but holds its shape.

Set the oven temperature to 400°F. Roll out the chilled dough on a floured surface into a 12-inch circle and fit it into a 9-inch pie pan. Line the crust with parchment paper and fill with pie weights or dried beans. Bake for 10-12 minutes until the edges are set and slightly golden. Carefully remove the weights and parchment, then bake uncovered for an additional 3-5 minutes until the crust is lightly golden.

While the crust cools, blend together the sugar, yogurt, eggs, lemon zest, and lemon juice in a mixing bowl until smooth and creamy. The mixture should be well combined without any lumps.

Once the rhubarb compote has cooled slightly, spread it evenly over the cooled crust. Pour the prepared lemon filling on top, making sure it covers the rhubarb completely. Return the pie to the oven and bake at 375°F for 20-25 minutes, until the edges are set and the center jiggles slightly.

Remove the Best Rhubarb Lemon Pie from the oven and allow it to cool for at least 2-3 hours at room temperature. For an enhanced texture, refrigerate the pie for a while before slicing. Serve chilled or at room temperature, optionally garnished with a dollop of whipped cream.