Prepare the Thyme-Honey: Warm the honey and thyme in a small saucepan over medium-low heat, stirring frequently, for about 10 minutes. Remove from the heat and allow to cool to room temperature. Strain out and discard the thyme before using.
Prepare the Whipped Ricotta: Place the ricotta in a food processor and pulse until smooth and fluffy, about 2 minutes. Add 2 tablespoons of the thyme-honey and whip again for about a minute. Taste and add more honey if desired and a pinch of sea salt. Pulse again to combine. Keep at room temperature until ready to serve. (If making in advance, store in the fridge and let come to room temperature before serving).
To Assemble: Toast bread slices. While the bread is still warm, spread the whipped ricotta onto each slice. Next, layer on one of each of the citrus slices (largest to smallest, overlapping). Drizzle everything with the thyme-honey and a pinch of sea salt. Serve immediately.
Note: reserve extra whipped ricotta and thyme-honey for future use.
Recipe adapted from: http://yestoyolks.com