Mix together the flour, salt, yeast, sugar and cardamom. Add the melted butter and mix until you get a rough paste
Mix in the milk - it should become soft and smooth. Stir so that it is well incorporated then tip onto a surface and knead a couple minutes. It will feel a little greasy, but don't worry. Put the dough in a bowl, cover and leave to rest for approx 30min. This is just a short proof - you don't want it to double in size.
Meanwhile, make the filling. Roughly chop the dates and put them in a small pan along with the cardamon and some water. Warm over a medium-low heat until the dates soften and break up. If it becomes smooth enough, just add the oil and warm a little more as you stir to combine but in most cases, it will be best to blend it. If you have an immersion blender, you can do this in the pan, otherwise transfer to a blender/small food processor, blend, then return to the pan and mix in the oil. To spread best, it's best to be gently warm.
Preheat the oven to 350F/175C.
Lay a silicone mat or a layer of parchment on your work surface and line a baking sheet with a silicone cookie sheet or parchment.
Tip the dough onto the lined work surface and roll the dough into around 11 inches square (28cm) or else a little narrower one way than the other but similar overall. Dab the date filling onto the top and spread all over the dough leaving a small strip without any on the two longer ends, if rectangular, or else two opposite edges.
Roll from one of the ends that doesn't have filling to the edge and form a roll. Finish by having the other end on the bottom so it seals together, and you can roll it a little more to become smooth against the roll.
Using a serrated knife, carefully cut the roll into slices, either approx 1in/2.5cm thick or thinner, as you prefer. You should get around 12 or so. Carefully transfer the slices to the baking sheet, standing on end and if need be, gently pressing down slightly to help them stand. You can also lay on their side if you prefer.
If you like, brush the top with a little egg wash or milk to help them brown, and you can also sprinkle on a few nigella seeds if you have some. Bake for approx 15 - 20 minutes until lightly golden brown. Delicious served warm from the oven but also good room temperature.