Melt 6 tablespoons (85g) of butter in a small saucepan. Remove from the heat and add 3 of the bay leaves. Let steep for 1 hour.

Preheat the oven to 350F / 180C. Butter a 9-inch loaf pan (or equivalent). Dust with flour and tap out any excess. If possible, line the bottom with parchment paper.

If you have a flat-bottomed pan, dab one side of the remaining 7 bay leaves with a little bit of butter and place the leaves, evenly spaced, on the bottom of the prepared pan, buttered side down.

In a large bowl, whisk together the flour, sugar, baking powder, and salt.

In a small bowl, whisk together the eggs, sour cream, orange zest, and vanilla until combined.

Barely rewarm the butter to liquify it and pluck out the bay leaves. Whisk the butter into the egg mixture.

Gently stir the egg mixture into the dry mixture, just until the batter is smooth. Do not over mix.

Scrape the batter into the prepared pan, being careful not to disturb the leaves.

Put the remaining 1 tablespoon of softened butter into a plastic bag, snip off a corner, then draw a straight line of the butter down the center of the cake.

Bake for 40 to 50 minutes, until a toothpick inserted into the center comes out clean.

Remove from the oven and let cool for 10 minutes. Run a knife around the perimeter of the cake and then tip out onto a cooling rack, remove leaves, and let cool completely before glazing.

To make the glaze, combine the powdered sugar, orange juice, and orange liquor (if using). Stir until smooth, then spread the glaze over the cooled cake.