For the tart shell, pulse the flour, cinnamon, 1/4 teaspoon salt and 1/4 cup sugar in a food processor until combined. Add 1/2 cup chilled cubed butter and pulse it until the mixture looks crumbly. Add the egg and vanilla extract and mix until the dough starts to clump.
Pat the dough into a 1-inch-thick disk, cover tightly with plastic wrap and chill in the refrigerator for 1 hour up to 3 days.
Remove the dough from the refrigerator and let it warm slightly. On a lightly floured work surface roll out the dough into a rough circle, about 12-inches in diameter and 1/8-inch-thick.
Carefully transfer the dough to a 9-inch tart pan with a removable bottom and trim the excess. (Extra dough can be stored in the refrigerator up to 3 days or frozen up to 1 month.)
Prick the bottom and sides of the dough with a fork. Freeze for 30 minutes.
Preheat the oven to 375 degrees F.
Line the dough with aluminum foil and fill with dried beans, rice or pie weights. Bake for 25 minutes until the tart starts to turn light brown. Remove the foil and weights and bake for an additional 10 minutes.
To make the caramel, combine the granulated sugar and water into a medium saucepan with high sides over medium-low heat, stirring frequently until the sugar has dissolved. Increase the heat and bring the caramel to a boil without stirring. You can gently swirl the pan especially when it starts to brown. Brush down the sides of the saucepan with a wet pastry brush as necessary.
When the caramel is a deep amber color, remove it from the heat and whisk in the heavy cream, butter, honey and vanilla extract. Then stir in the nuts.
Pour the filling into the crust and bake for 15-20 minutes until the filling bubbles and the nuts are toasted. Cool on a wire rack before serving. Serve warm or at room temperature.