If the squash is not already cooked, peel it and steam it until it melts. Then mash the cooked squash with a fork to obtain a purée.
In a bowl, beat the egg with the sugar until the mixture is frothy.
Add the spices: cinnamon, vanilla, nutmeg and ginger, and the zest if you put some.
Pour the mixture over the squash puree. Mix well to homogenize the stuffing.
Stir in almond powder and flour and mix.
Add the fresh cream and mix again. You should obtain a fairly liquid but still thick texture.
In a large pie dish (I took a 30 cm diameter dish), place the dough in the center of the dish, and roll it down with your fists to stretch it towards the edges. The dough doesn't have to rise all the way up to the edges depending on the size of the dish.
Pour the stuffing over the dough. You can sprinkle with slivered almonds.
Bake at 195 °C for 35 minutes, and leave 5 more minutes once the oven is turned off (check the baking time according to your oven...).
Take the tart out and place it on a wire rack to let it cool down.
Serve warm or cold. For an even more gourmet touch, serve with a scoop of vanilla or caramel ice cream or whipped cream.