Butter the pan and dust with flour and sprinkle demerara sugar into the bottom
Zest the two oranges and set aside 1 tsp of zest for the icing. and cut into halves for juicing. Strain the juice into a bowl and set aside. The juice from 1 1/2 oranges should yield roughly 1/4 cup of juice
In a large bowl, break the five eggs. Add the sugar and beat until the sugar starts to dissolve (about 3 minutes with a handheld mixer on a low setting)
Add the chamomile tea and continue to blend for another 2-3 minutes
Add the juice, zest and olive oil whisk until just blended
In a medium bowl, whisk together the flour, salt and baking powder. Add the flour slowly to the egg/sugar mixture, mixing with a wooden spoon until incorporated
Pour into pan and bake for 45 minutes at 350°
Cool on a rack
While the cake is cooling, beat the zest, tea, confectioners sugar together until thick and creamy. Thin slightly with the half and half and glaze the cake until it's cooled completely