I recommend making the dough using a stand mixer fitted with the dough hook attachment, as it'll be very soft and sticky.

Make the psyllium gel: In a bowl, mix together the psyllium husk and lukewarm water. After about 30-45 seconds, a gel will form.

In a large bowl or the bowl of a stand mixer (if using), whisk together the tapioca starch, millet flour, sorghum flour, sugar, instant yeast, baking powder, xanthan gum and salt.Tip: If using active dry yeast instead, you need to activate it first. Mix it together with the lukewarm milk and the sugar. Set aside for 5-10 minutes, or until the mixture starts frothing. Then, add it to the dry ingredients along with the rest of the wet ingredients.

Add the milk, egg and oil to the psyllium gel, and mix well to combine.

Make a well in the middle of the dry ingredients and add the psyllium gel-egg mixture.

Knead the dough until smooth and all the ingredients are evenly incorporated, then knead for a further 4-5 minutes (if using a stand mixer) or 6-8 minutes (if kneading it by hand). Use a rubber spatula to occasionally scrape along the sides and bottom of the bowl to prevent any dry patches of unmixed flour.Tip: This extra kneading time will make the dough EXTRA smooth, which is the key to beautiful gluten free buns.

The final dough will be VERY soft and sticky – that’s okay, you’ll be working on a generously floured surface (and with floured hands) so it shouldn’t be a problem. Resist the temptation to add more flour to the dough, as that can make the final buns too dense and dry.Tip: If you find the dough too sticky to easily handle (even on a floured surface and with floured hands), you can chill it in the fridge for about 1 hour before proceeding to the next step. This will make the dough slightly less sticky and therefore easier to handle.

When it comes to shaping these gluten free buns, it’s important that you work on a generously floured surface and with floured hands.

Turn out the dough onto a generously floured surface, and dust the top of the dough with flour as well. Give it a gentle knead (with floured hands) and shape it into a ball.

Divide the dough into six equal portions (each should weigh about 86g) and shape them into smooth balls. You’ll work with one dough ball at a time, so keep the others covered with a sheet of plastic wrap/cling film or a tea towel to prevent them from drying out.

Roll out the dough ball into a roughly 7-inch (18cm) circle.

Mix together the grated cheddar and mozzarella, and then arrange them around the edges of the dough circle, creating an approximately ¾-inch (2cm) border of cheese. You can pinch the cheese together with your fingertips to make it more compact – that’ll make the buns easier to shape.

Fold the edges of the dough circle over the cheese, overlapping the dough as needed, and press down to seal. Make sure that there are no gaps, as that would allow the cheese to leak out during baking.

Repeat with the rest of the dough and cheese, and then arrange the shaped buns on a lined large baking sheet as far apart as possible, as they’ll expand during both proofing and baking.

Lightly cover the buns with a sheet of plastic wrap/cling film (to prevent them from drying out) and proof in a warm spot for about 1 hour to 1 hour 15 minutes, until they're slightly puffed up. Because of the way in which they’re shaped, they won’t quite double in size – that’s okay, they’ll still have the perfect crumb in the end.

About 20 minutes before the buns finish proofing, start preheating the oven. Adjust the oven rack to the middle position and preheat the oven to 375ºF (190ºC).

Egg wash the edges of each bun.

Spoon about 1 tablespoon of tomato sauce into each “well”, spreading it out so it covers the whole “well” of the bun as well as part of the raised edge.

Sprinkle generously with grated cheese and top with sliced olives (or other toppings of choice).

Bake the buns at 375ºF (190ºC) for about 18-20 minutes or until the dough is deep golden brown and the cheese is gooey, bubbly and it starts browning in spots.

Allow the buns to cool for 5-10 minutes before you serve them. Just like any pizza, these are at their very best when they’re still slightly hot, so you get to experience them in all their soft, cheesy, gooey glory. You can also sprinkle on some chopped fresh basil just before serving.