Heat the oil in a medium pan, then
gently fry the garlic for 10 mins until
softened but not coloured. Set aside.
Heat oven to 220C/200C fan/gas 7.
Put the flour, salt and baking powder into a food processor, then whizz in the butter until it disappears. Tip into a large bowl, then make a well in the middle. Warm the yogurt and milk together in a microwave for 1 min or in a pan; it should be hot and may well go a bit lumpy-looking. Tip into the bowl and quickly work into the flour mix using a cutlery knife. As soon as it's all in, stop.
dough onto a floured surface, bring it
together with floured hands, then press
out to a large rectangle. Scatter over the
potatoes, chopped rosemary, garlic, some
of its oil and most of the cheese. Knead
a few times, shape into a round, then
lift onto a floured baking sheet.
Score the top, scatter with the rest of
the cheese, poke in a few rosemary sprigs,
then drizzle with the remaining oil. Bake
for 25 mins until risen, golden and sizzling
around the edges. Best eaten just warm.