1 Make the tart dough: Whisk together the flour, sugar, cinnamon, nutmeg and salt. Add the cut up pieces of butter and use a pastry cutter to cut into the flour mixture until the butter pieces are no bigger than a pea. (You can use a food processor for this if you want.)
Sprinkle with vanilla and add 3 tablespoons of ice water. Use a fork to work the water and vanilla into the dough. (You can use a food processor.) Add up to a tablespoon more of ice water, just enough so that the dough easily sticks together when you pinch it with your fingers.
Form the dough into a ball, kneading once or twice if necessary, and flatten into a disk. Wrap the dough disk in plastic and chill for 1 hour.
2 Roll out the dough, place in tart pan, freeze: Preheat oven to 375°F (190°C). Remove dough from refrigerator and let sit for 10 minutes. Place the dough on a lightly floured clean surface. Roll out the dough to a 12-inch round. Place the dough in a 9 1/2-inch-diameter tart pan with a removable bottom.
Press the dough down and into the sides. Roll the rolling pin over the top of the tart pan to even off the top edges.
Pierce the bottom of the dough in the tart pan all over with fork. Freeze for 30 minutes.
3 Pre-bake the crust: Bake the crust at 375°F for 20 minutes, piercing the bottom with fork if bubbles form. Transfer to a rack to cool.
4 Make the caramel nut filling: Put sugar and 1/4 cup water in heavy medium saucepan with high sides. Heat on medium-low heat and stir until sugar dissolves.
Once the sugar has dissolved, increase the heat to medium high. Boil without stirring until caramel is deep amber color, occasionally swirling the pan, about 10 minutes. Reduce heat to medium.
Slowly stir in the cream. Be careful as the mixture will bubble up significantly (this is why we are using a high sided pot). Stir until the caramel is smooth.
Add the butter, honey and vanilla. Stir until the butter has all melted.
Stir in all of the nuts.
5 Bake: Pour caramel mixture into the pre-baked crust. Bake at 400°F (205°C) 20 minutes. Remove from oven to cool completely on rack.
Serve with whipped cream or vanilla ice cream (optional).