In small saucepan, stir together 3/4 cup (175 mL) of the sugar, water and lemon juice; bring to boil over medium-high heat, stirring occasionally. Boil, without stirring, until deep amber colour, about 5 minutes, watching carefully because sugar burns very quickly. Immediately pour into ungreased 10-inch (25 cm) pie plate, tilting to coat bottom. (Caramel sets very quickly.)

In large bowl, whisk together squash, remaining 1/2 cup (125 mL) sugar, eggs, egg yolk, vanilla, cinnamon, ginger, nutmeg and salt. In small saucepan, heat milk with cream until hot; gradually whisk into squash mixture. Pour over caramel in pie plate.  Place in large baking pan. Fill baking pan with enough hot water to come halfway up sides of pie plate.

Bake in 325°F (160°C) oven until flan is set but centre jiggles slightly and knife inserted in custard comes out clean, about 1 hour. Remove from water and let cool completely.  Refrigerate, loosely covered, for 4 hours but preferably overnight. To unmould, run knife around edge of custard. Invert large flat plate with shallow sides on pie plate. Holding tightly against pie plate, carefully turn over and invert flan onto plate. Serve in wedges with caramel sauce spooned over top. 

* For this recipe, you’ll need a squash weighing 3 to 3-1/2 lb (1.5 to 1.75 kg). Pierce squash in several places, then bake in the oven or microwave until very tender. Cut in half and discard seeds. Scrape squash from peel.  Purée in food processor fitted with metal blade. Strain in sieve for 30 minutes to remove excess water. Measure out 1-1/2 cup (375 mL). Any remaining squash can be frozen and used in soup, muffins, pie or bread.