The night before: Combine the heavy cream with 1 tablespoon of lemon juice. Let sit out a room temperature.
Preheat oven to 375 degrees. Make simple syrup: Combine 3 cups water with 3 cups sugar in saucepan. Bring to a boil and cook until all sugar has dissolved, about 10 minutes. Place figs in simple syrup and simmer for 5 minutes. Remove figs and place on the bottom of a large baking dish.
Make crumble topping: In a medium bowl, combine flour, sugars, and salt. Cut in cold butter with a pastry cutter or fork. If butter begins to melt, place in refrigerator or freezer and let cool down for 10 minutes. Top figs with crumble. Bake for 30 minutes until bubbly.
Using a stand or hand mixer, whip cream. To serve, top crumble with whipped cream.