Center a rack in the oven, and preheat it to 350. Butter an 8 1/2-inch loaf pan (Pyrex works well), dust with flour and tap out the excess. (For this cake, bakers’ spray isn’t as good as butter and flour.) Place on a baking sheet.
Whisk the 1 1/2 cups flour, baking powder, cardamom, ginger and salt together.
Put the sugar in a large bowl, and grate the zest of the lemon(s) over the sugar. Squeeze the lemon(s) to produce 3 tablespoons juice, and set this aside. Using your fingers, rub the sugar and zest together until the mixture is moist and aromatic. One at a time, add the eggs, whisking well after each. Whisk in the juice, followed by the heavy cream. Still using the whisk, gently stir the dry ingredients into the batter in two additions. Stir the vanilla into the melted butter, and then gradually blend the butter into the batter. The batter will be thick and have a beautiful sheen. Scrape it into the loaf pan.
Bake for 70 to 75 minutes (if the cake looks as if it’s getting too dark too quickly, tent it loosely with foil) or until a tester inserted deep into the center of the cake comes out clean. Transfer to a rack, let rest for 5 minutes and then carefully run a blunt knife between the sides of the cake and the pan. Invert onto the rack, and turn over. Glaze now, or cool to room temperature.
For the glaze: Bring the marmalade and water to a boil. Brush the glaze over the top of the warm cake, and allow to it to set for 2 hours. The glaze will remain slightly tacky.
When the cake is completely cool, wrap in plastic to store. If it’s glazed, wrap loosely on top.