Heat the oven to 350°F and butter an 8-inch springform well, sides included.
Simmer the blueberries with the teaspoon of honey for 5 minutes until they burst and thicken, then cool.
Crack the eggs into the yogurt and whisk until no streaks of yolk are left.
Whisk in the honey, cornstarch, vanilla and lemon zest until the batter is pale and glossy.
Pour it into the tin in one continuous ribbon so no air pockets get trapped.
Spoon three blobs of the compote on top and drag a skewer through in loose S curves.
Bake 45 minutes. The edges set and the center still moves slightly when you nudge the tin.
Cool on the counter, then chill at least 4 hours. It firms as it goes cold, not in the oven.
