To make the ginger crème fraîche, finely grate the stem ginger into the crème fraîche along with a spoonful of the syrup. Combine, then ideally transfer into a muslin cloth bag and hang in the fridge overnight. Leave a small bowl underneath to catch the excess liquid.
Transfer to an airtight container until you are ready to use.
Warm the cream in a large saucepan over a low heat until it reaches 50°C.
Whisk the egg yolks and honey together in a large bowl until combined, then pour over the hot cream, whisking continuously; it should start to thicken slightly. Pass the custard through a fine sieve and leave to rest for 5 minutes. Skim off the layer of foam that will form on top.
Preheat the oven to 110°C. Half-fill the blind-baked tart case with the cooled custard, then carefully transfer to the oven. Bake for 45 minutes–1 hour. You are looking for a slight wobble in the centre of the custard. Leave to rest for a couple of hours before you cut into it.
To serve, slice the tart into wedges and serve with a generous spoonful of ginger crème fraîche