Preheat the oven to 350°F (175°C) and oil a bundt pan generously.

In a stainless steel pot, combine ½ cup of sugar, ½ cup of water, and lemon juice over medium heat and stir gently until dissolved. Boil undisturbed until light golden brown, about 8-10 minutes.

Pour the caramel into the prepared bundt pan, tilting to coat the bottom evenly. Set aside to cool.

Cut the gluten-free bread into bite-sized pieces and soak in 800 ml of warm almond or soy milk for about 10 minutes.

Whisk together 7 eggs, 1 cup of sugar, 1 tablespoon of lemon zest, and 1 teaspoon of vanilla extract until smooth.

Slowly pour the egg mixture over the soaked bread, folding gently until well combined.

Transfer the mixture into the bundt pan over the caramel, spreading evenly.

Place the bundt pan in the center of a baking sheet and fill with 2 inches of hot water. Bake for about 1 hour or until a toothpick comes out clean.

Let cool for about 20 minutes, then run a knife around the edges and invert onto a serving plate.