With the rack in the lowest position, preheat the oven to 180 °C (350 °F). Butter and line a 23 x 13-cm (9 x 5-inch) loaf pan with parchment paper, letting it hang over two sides.
In a skillet, brown the bacon. Remove any excess fat. Add the leek and sauté for about 1 minute. Let cool.
In a bowl, combine the flour, baking powder, salt, and pepper. Set aside.
In a large bowl, beat the eggs and honey with an electric mixer until the mixture triples in volume, about 5 minutes. On low speed, add the oil and mustard and then add the dry ingredients alternately with the milk. Add the bacon, cheese, and herb mixture and stir with a spatula.
Spoon into the prepared pan. Bake for 50 to 55 minutes or until a toothpick inserted in the centre of the cake comes out clean. Remove from the pan and let cool on a wire rack. Serve warm or cold with cultured cream or butter. Delicious with Cold Carrot Soup.
This cake is perfect for a picnic with cold meats and firm cheeses.