To make the dough, place all of the ingredients into (apart from the vegetable oil) into the bowl of a stand mixer fitted with a dough hook. Mix on a low speed until it comes together into a dough then turn up the speed and continue to mix until it is smooth and elastic and comes away from the sides of the bowl cleanly. You can knead the dough by hand if you prefer but it is very sticky.
Place in a bowl, cover with clingfilm and set aside until doubled in size, about 1 hour. You can also place the dough in the fridge to rise overnight, allow to come up to room temperature for half an hour before proceeding with the next step.
Tip the dough out onto a lightly floured surface and roll it out to about 1cm thick. Use a 7-8cm round pastry cutter to cut out circles of dough, then use a 3-4cm one to cut a hole out of the centre of each (I used the wide end of a large piping nozzle as I didn't have a cutter small enough). Knead together the scraps until smooth then re-roll the dough and cut out more rounds; you should be able to get about 8 doughnuts. I rolled the leftover scraps into a couple of small balls and flattened them slightly to make a couple of mini cats. You can also make fewer ring doughnuts and keep the holes to make more mini cat doughnuts.
Place the doughnuts well spaced apart on a baking sheet lined with lightly oiled greaseproof paper; cover loosely with oiled clingfilm and set aside to rise for about 40 minutes until puffy.
Heat a deep fat fryer or large pan of oil to between 170C (338F) and 180C (356F). Cut the paper around each doughnut so that each one is sitting on it's own square of paper. Lift the doughnut on it's parchment into the oil; the paper will come away from the doughnut and you can fish it out with tongs. I find this the easiest way to transfer the doughnuts into the fryer as they are quite soft and sticky.
Fry the doughnuts a couple at a time for a couple of minutes per side until golden, they should reach 100C (212F) inside, I use a probe thermometer to check each one is done.
Use a slotted spoon to lift the doughnuts out onto a plate lined with kitchen paper to drain.
Cut a couple of small slits in the top of each doughnut for the ears to fit in. Dip the rounded end of an almond into the melted chocolate and stick it into one of the slits; repeat to make the rest of the ears. Set aside until the chocolate has hardened.
To make the glaze, place the chocolate in a bowl that is wide enough to dip the doughnuts in. Heat the cream until just boiling then pour it over the chocolate; leave for a couple of minutes then stir until melted and smooth. Stir in the icing sugar. Add food colouring a little at a time (if using), until the glaze reaches the desired shade, a little goes a long way with the black extra so just add a bit at a time. If the glaze is a bit too thick for dipping, you can thin it with a little bit more warm cream.
Dip the tops of each doughnut into the glaze, letting the excess run off before placing them on a wire rack. If the glaze cools too much and becomes too thick, you can give it a short blast in the microwave to re-melt it.
Once the glaze has set a little, use a pink pearl to make the cat's nose, and two white pearls for the eyes. Pipe on the mouth and whiskers with the white writing icing, and pipe a tiny dot of black writing icing on each eye to make a pupil. Repeat with the remaining doughnuts.
Store in an airtight container, best eaten on the day they are made.