Finely grate the zest of 1 of the citrus fruits and reserve the zest for the cake batter. Cut the citrus fruit in half, juice it, and strain the juice; you should have 1/3 cup juice. (There’s a chance you may need a second citrus to yield sufficient juice.)

Slice the remaining citrus fruits into very thin rounds—not paper thin, mind you, but no more than 6 mm thick. Remove and discard any seeds. If using thicker-skinned citrus such as navel oranges, slice the citrus 6 mm thick, place the slices on a plate, and microwave on high for 3 minutes for navel oranges. This helps ensure the thick peel softens without turning the fruit clinging to it to mush.

In a medium nonreactive saucepan over low heat, combine the orange juice, lemon juice, sugar, salt, and orange slices and bring to a slow simmer. Cook for 6 to 7 minutes, until the peels are tender and the centers of the orange slices are starting to become tender and translucent but are not falling apart. If the peels aren’t yet tender enough to cut with a fork, keep simmering until they are.

Using a slotted spoon, carefully transfer the orange slices to a plate. Continue to simmer the syrup until it reduces to 1/2 cup, anywhere from 5 minutes to 15 minutes, depending on how long you simmered the orange slices and the size of your pan. Remove from the heat.

Preheat the oven to 190°C. Butter a springform cake pan.

Toss the butter and sugar in the bowl of a stand mixer fitted with the paddle attachment and beat on medium speed until fluffy. With the mixer still running, add an egg and mix until it’s completely and indisputably incorporated before adding the second egg. When the second egg is similarly incorporated, sprinkle the grated orange zest reserved from the glaze recipe over the batter and mix until combined.

In a bowl, sift together the semolina flour, all-purpose flour, baking powder, and salt.

Gently mix the flour mixture into the batter, a little at a time, and mix just until no white streaks of flour remain. Pour the batter into the buttered cake pan and smooth the surface.

Arrange the glazed oranges on the batter in a single layer, first pausing to allow any excess glaze to drip from the oranges back into the pan before placing them on the cake. Reserve the remaining glaze in the pan. (You may also end up with some extra citrus slices, which is intentional since some of the slices may fall apart during simmering. Any extras are lovely to nibble or spoon over yogurt.)

Bake the cake for 15 minutes. Reduce the oven temperature to 180°C and bake the cake for 35 to 40 minutes more for a total of 50 to 55 minutes, until the cake is an even golden brown and a toothpick inserted in the centre comes out clean.

Let the cake cool in the pan on a wire rack until just warm. Using a wooden skewer, poke holes all over the surface of the cake. Brush the remaining glaze over the top using a pastry brush. Let the cake cool to room temperature on a wire rack before removing it from the pan or simply slice and serve the cake straight from the pan.