In a small pan on medium-low heat, add the oil and rosemary. Turn the heat off and steep until the oil is fragrant and the rosemary is wilted, about 15 minutes.
Add the ricotta to a food processor along with the lemon zest, lemon juice, a pinch of salt and 1 tablespoon of the rosemary oil. Blitz until light and fluffy. Taste for seasoning, then remove to a serving dish.
Using 2 tablespoons of the rosemary oil, brush the bread slices lightly on both sides. Place the bread on a grill pan over medium-high heat and grill until charred, 3 to 5 minutes per side. Remove to a plate or basket for serving.
Drizzle the remaining rosemary oil over the top of the whipped ricotta, then add a light drizzle of honey and top with a final pinch of salt. Serve with the grilled bread.
