Preheat your oven to 375°F (190°C). Grease an 8x11.5 inch baking dish with butter or non-stick spray and sprinkle 1/4 cup of sugar evenly across the bottom.

Rinse the mixed berries thoroughly and trim them to a uniform size. Combine the berries with the optional berry liquor in a mixing bowl and let them sit for 10 minutes.

In a large mixing bowl, whisk together 8 eggs, 1 1/2 cups of sugar, 2 teaspoons of vanilla extract, 2 cups of heavy cream, and 1 cup of milk until smooth.

Layer half of your cubed brioche bread (about 4 cups) into the prepared baking dish and pour half of the custard mixture gently over the bread.

Sprinkle half of the berry mixture over the custard-soaked brioche.

Repeat the process with the remaining brioche bread and custard, adding the leftover berries on top.

Bake for about 55 minutes to 1 hour until the top is golden and the custard is set but jiggly.

Remove from oven and allow to cool for at least 15 minutes before serving.