Set an oven rack in the center position and heat the oven to 350°F. Coat a 9x13 inch baking dish thoroughly with butter or oil, covering the bottom and all sides to prevent sticking and promote even browning.

Whisk the room temperature eggs, vegetable oil, both sugars, water, and vanilla extract in a large bowl until the mixture appears smooth and lightly emulsified, approximately 1-2 minutes. Room temperature eggs blend more easily with oil for better batter consistency.

Combine the 2 cups flour, 2 teaspoons baking powder, 3/4 teaspoon salt, and cardamom in another bowl, whisking to distribute evenly. Fold this dry mixture into the wet ingredients with a spatula, mixing only until just incorporated to maintain tenderness. Fold in the minced candied ginger and lemon zest, distributing evenly.

Prepare the crumble by whisking together the 1/2 cup flour, 1/2 teaspoon baking powder, 1/4 teaspoon salt, both sugars, and cinnamon in a separate bowl. Cube the cold butter and add to the mixture, then work it in with your fingertips until you achieve a coarse, crumbly texture with some pea-sized butter pieces visible. Mix in the chopped walnuts.

Transfer the batter to your greased pan, spreading it to create an even layer. Arrange the quartered figs evenly across the batter surface—they will partially sink during baking. Scatter the crumble topping uniformly over everything, pressing down lightly to help it adhere without compacting excessively. Bake for 50 minutes, checking doneness with a toothpick inserted into the cake (not the figs) that comes out clean or with minimal moist crumbs.

Take the cake from the oven and allow it to rest in the pan for a minimum of 15 minutes before cutting. This cooling period lets the structure firm up for clean slicing. Enjoy warm or at room temperature, as the flavors continue to develop while cooling.