Line 2 large or 3 smaller loaf tine with baking parchment. Preheat the oven to 180 degrees Celsius.
Cream the butter and sugar until light and fluffy
Add the mashed banana, eggs, lemon zest and vanilla, beating well.
Sift the flour, spices and salt together and fold half of this into the cake batter
Fold in half of the tea. Add the remaining dry ingredients, folding in carefully then finish with the rest of the tea.
Spoon into prepared loaf tins and place in the oven
Bake for 30 minutes, then lower the temperature of the oven to 160 degrees Celsius and cook for a further 20 minutes or until a skewer inserted into the centre of the loaves, comes out clean.
Once the loaves are cooked, remove form the oven and leave to cool in the tins for 15 minutes.
If using the glaze, mix the icing sugar, lemon zest and tea together to form a runny icing.
Unmould the banana loaves from their tins, removing the baking parchment. Drizzle with the earl grey tea glaze. Serve in thick slices with a cup of tea.