Combine the whole milk, heavy cream, and the split vanilla bean (seeds and pod) in a saucepan. Heat over medium‑low until just below boiling, stirring occasionally.

In a mixing bowl, whisk the egg yolks with 30 g granulated sugar until the mixture turns pale and slightly frothy.

Slowly pour a thin stream of the hot milk mixture into the yolk mixture while whisking constantly. Return the combined mixture to the saucepan and cook over low heat, stirring with a wooden spoon, until the custard reaches about 78 °C and coats the back of the spoon.

Trim the ends off the brioche loaf and slice into four 2‑inch‑thick pieces. Leave the crusts on for structural support.

Add the knob of butter and the splash of vegetable oil to the skillet. Heat over low, allowing the butter to melt and foam without browning.

Place one brioche slice in a shallow dish and pour the custard over it, ensuring both sides are fully saturated. Let it soak for about 2 minutes per side (total 4 minutes).

Transfer the soaked slice to the hot skillet. Cook for 2 minutes until the underside is golden‑brown and crisp.

Turn the toast and cook the other side for another 2 minutes, maintaining the same colour.

Sprinkle 20 g caster sugar over the toast in the pan. Allow it to melt and turn amber, about 2 minutes, then sprinkle a pinch of flaky sea salt.

Remove the toast from the pan onto the serving tray and let it rest for 2 minutes. This lets the interior custard finish setting without over‑cooking.

Repeat steps 6‑10 for the remaining brioche slices, adjusting soaking time if using a different bread type (white loaf ≈ 2½‑3 min/side, sourdough ≈ 4 min/side).

In a small bowl, gently fold together mascarpone, icing sugar, a pinch of salt, orange zest, and the splash of Hennessy until smooth. Do not over‑whisk.

Arrange the caramelized French toast on plates, dollop the mascarpone mixture on top, and finish with a light drizzle of any remaining caramel from the pan. Serve immediately.