Remove dough from processor, knead lightly to bring it together as a ball. Wrap in plastic film, chill for 1 hour.

Preheat the oven to 400 degrees F.

Generously dust work surface with potato starch, Roll chilled dough out to a rough square that’s slightly bigger than 11″ x 11″. Carefully transfer rolled dough to tart pan, smoothing the bottom and pressing the dough into the sides of the pan. Trim any excess dough that extends past the top of the pan, prick the flat (bottom) surface of the crust a few times with a fork.

Bake for 20 minutes or until golden brown. Remove from oven and allow to cool. Turn oven down to 350F.

While baking the crust, prepare your roasted roots.

Line 2 large baking sheets with parchment paper, spray with pan spray.

Peel all vegetables except for the beets. Carefully slice them into ¼″ thick rounds – we use a mandoline slicer for this. Arrange onto one of the prepared pans, spray with pan spray.

Repeat with golden beets, arranging on one half of the second prepared pan. Repeat with red beets, arranging on the remaining space on the second pan. (Fussy, I know.. but beets “bleed” like crazy!). Sprinkle veggies on both pans with salt and pepper. Roast until tender, about 30 minutes.

As veggies are roasting, prepare your custard:

In a small saucepan, melt butter over medium heat. Add garlic, horseradish, and white wine, whisk until smooth; gently bring to a simmer.

In a small bowl whisk together potato starch and egg yolks until smooth. Add milk, continue whisking until smooth. Add milk mixture to pot, simmer over medium heat until very thick. Once custard has thickened to your liking, remove from heat.

Spread hot custard in crust, top with roasted root veggies, serve immediately.