Heat half-and-half in a saucepan over medium-low heat until just boiling.

Add fresh ginger slices, remove from heat, cover, and let steep for 30 minutes.

Divide crystallized ginger among eight ramekins, covering the bottoms.

Preheat oven to 300°F (150°C).

Whisk whole eggs, egg yolks, sugar, and ground ginger in a bowl.

Reheat half-and-half to a boil; strain into egg mixture (discard ginger).

Combine thoroughly.

Whisk mixture back into saucepan and cook over low heat, stirring constantly, until custard coats the back of a spoon. Do not boil.

Divide custard among ramekins.

Place ramekins in a baking dish; pour hot water into the dish, reaching two-thirds up the sides.

Bake until a knife inserted in the center comes out clean, about 30 minutes.

Serve warm or chilled with whipped cream and remaining crystallized ginger.