Preheat your oven to 350°F (175°C) and oil the inside of the bundt cake mold.

In a heavy-bottomed pot, combine sugar, water, and lemon juice over medium heat, stirring until sugar dissolves. Allow it to cook without stirring until rich golden color is achieved, about 8-10 minutes.

Pour the caramel into the prepared mold and let it cool and set.

Cut the gluten-free bread into small pieces and place them in a mixing bowl. Warm the almond milk and pour it over the bread, letting it soak for about 5 minutes.

In a separate bowl, whisk together the eggs and sugar. Add the soaked bread, lemon zest, and vanilla extract, folding gently.

Pour the pudding mixture into the bundt mold over the cooled caramel, and bake in a water bath for about 1 hour.

Once baked, cool completely at room temperature before inverting onto a serving plate.