Preheat the oven to 350 degrees F. Generously butter an 8 1/2-x-4 1/2-inch loaf pan and place the pan on a baking sheet.
Whisk together the flour, ground almonds, if you're using them, baking powder and salt.
Put the sugar and zest in a medium bowl and, with your fingertips, rub the zest and herbs into the sugar until the sugar is moist and aromatic. Add the yogurt, eggs and vanilla and whisking vigorously until the mixture is very well blended. While whisking, add the dry ingredients, then switch to a large rubber spatula and slowly add in the oil. You'll have a thick, smooth batter with a slight sheen. Scrape the batter into the pan and smooth the top.
Bake for 50 to 55 minutes, or until the cake begins to come away from the sides of the pan; it should be golden brown and a thin knife inserted into the center will come out clean. Transfer the pan to a rack and cool for 5 minutes, then run a blunt knife between the cake and the sides of the pan. Remove the loaf tin and cool to room temperature right side up on the rack.
Glaze: Put the marmalade in a small saucepan or in a microwave-safe bowl, stir in the teaspoon of the water and heat until the jelly is hot and liquefied. Using a pastry brush, gently brush the cake with the glaze.