In a wide skillet, combine the sugar, honey, and water, simmering until all the sugar is dissolved. Carefully place a single layer of citrus rounds into the liquid and simmer until the peels are tender and semi-translucent – about 20 to 25 minutes, turning each slice halfway through. Transfer candied slices to a parchment-lined baking sheet. Continue with remaining slices of citrus.
Note: These can be made ahead of time, stored on the baking sheet in the refrigerator wrapped tightly with plastic wrap.
Set the oven to 350 degrees. Grease and flour an 8″ round cake tin.
In a large bowl, combine the flour, sugar, baking powder, and salt. In another bowl, whisk together the honey, eggs, milk, and juice. Once combined, slowly drizzle in the olive oil while constantly whisking to create an emulsion. Make a well in the flour bowl and add the wet ingredients to the dry. Stir until just combined. Pour into the greased cake tin and tap on the counter to release any trapped air bubbles. Place in the middle of the oven and bake until the top springs back when touched and toothpick inserted into the middle of the cake comes out clean – about 40 to 50 minutes. Let the cake cool in the pan for a few minutes, run a knife around the edge, then turn onto a wire rack to cool completely before glazing.
Make the glaze. In a small bowl combine the sugar, milk, and vanilla and whisk until smooth. The consistency of the glaze should be similar to Elmer’s glue. If necessary add a bit more milk to thin. Pour the glaze over the middle of the cooled cake and let drip down the sides. Let the glaze set a bit before topping with the candied citrus slices. Serve at room temperature with a cup of hot tea.