For the croutons:
1) Preheat the oven to 200°C/ gas mark 6.
2) In a medium bowl, toss together the bread cubes and melted butter. Add the vanilla sugar and toss until the bread cubes are coated in the sugar. Arrange the bread cubes in a single layer on baking tray lined with greaseproof paper and bake until golden brown, about 8 to 10 minutes. Cool completely.
For the syrup:
1) In a small saucepan, bring the orange juice, lemon juice and caster sugar to a simmer over medium-low heat. Stir until the caster sugar has dissolved, about 2 to 3 minutes.
2) Add the blueberries and strawberries, and simmer until the fruit softens, about 6 to 8 minutes. Cool the syrup to room temperature.
For the ricotta:
1) Combine all of the ingredients in a medium bowl. Mix well.
For the dish assembly:
1) Divide the ricotta mixture between four decorative dessert bowls. Spoon the fruit syrup over the ricotta and top with the croutons. Garnish with the sliced mint.
For the vanilla sugar:
1) Place the caster sugar in the bowl of a food processor. Using a paring knife, slice the vanilla pod in half lengthwise and scrape out the seeds. Add the vanilla seeds to the caster sugar.
2) Pulse 10 to 15 times until the vanilla and sugar are combined. Cut the empty vanilla pod into 2 1/2cm pieces and place in a glass mason jar. Add the vanilla sugar to the jar and seal. Shake the jar before using.