Lemon Verbena and Polenta Cake with Chocolate Cardamom Cream

Health shops often sell lemon verbena in ‘tea’ form, if you’re unable to find a fresh tree. If you are fortunate enough to have fresh leaves, dry them on the window ledge or in an airing cupboard. Either way, grind the verbena to a fine powder in a spice grinder or use a mortar and pestle. Failing that, use the Australian ‘bush food’ lemon myrtle, or the finely grated zest of a lemon.