To Make the Crust:

1. Generously butter a 9-inch round tart pan. In a food processor, pulse to grind the hazelnuts for about 30 seconds. You want a smooth medium grind; not chunky, but not a nut butter either.
2. Add flour, sugar, and salt. Give them a quick pulse to blend together. Add butter and pulse into the dry ingredients a few times, until the mixture resembles coarse meal.
3. Add egg yolk and 1 tablespoon ice water. Blend until the dough forms a ball. If your mixture is still too dry, add another tablespoon of ice water.
4. Dump out dough onto a clean, floured work surface and bring it all together if there are any bits that haven’t clung to the ball. Flatten into a disc and then roll dough out into a circle that is larger than the mouth of the tart pan.
5. Press dough into bottom and up the sides of prepared pan. Cover and chill for 1 hour in the refrigerator, or 30 minutes in the freezer.
6. Preheat oven to 350°F. Poke holes all over the base of the dough. Line with foil and add pie weights or dried beans to blind bake the crust. Bake for 15 minutes, then remove from oven, and lift foil to remove the weights. Return to the oven for 10 minutes, until just beginning to turn golden.
7. Cool on the counter, then cover with plastic wrap and chill in the freezer for about 20 minutes before filling.

To Make the Filling:

1. In a small saucepan, melt the butter over medium heat until it starts to turn golden and smell nutty and toasty, about 5 minutes. Remove from heat and stir in vanilla. Set aside to cool.
2. In a medium bowl, whisk the eggs with 1 cup sugar and the lemon zest.
3. Slowly pour 1/4 cup of the egg mixture to the warm brown butter, whisking the entire time so your eggs don’t cook. Add the brown butter mixture back to the rest of the egg mixture, and whisk to combine.
4. Whisk in the flour and salt.
5. Pour the filling into the crust and bake for another 20-30 minutes at 350°F, or until golden and set (not jiggly in the center). Transfer to a rack to cool for about 1 1/2 hours.

To Make the Cranberry Topping:

1. In a saucepan, combine the remaining 3/4 cup sugar with the cranberries and water. Bring to a simmer over medium-heat and cook until the cranberries just begin to pop and the sugar dissolves without stirring, about 5 minutes.
2. Pour the into a bowl and sprinkle gelatin over the top. Stir, then refrigerate until cool for about 1 hour. Spread cooled cranberry gelatin on top of the tart.
3. Chill the tart thoroughly for about 4 hours before serving.