I assume you're here because you love bread... And if that's the case, let's be friends... best friends.
*NOTE: You can get purpose-built Pain de Mie pans (or pullman loaf pans), but I just used a 3 litre capacity loaf pan (commercial grade) topped with a heavy sheet pan weighted down with a cast iron skillet - it has to be heavy though, that dough has some serious push when it gets in the oven.
slightly adapted from here
250ml lukewarm water
250ml full cream milk
625g bread flour, plus extra for dusting
2 1/2 teaspoon sea salt
1 tablespoon honey
100g unsalted butter, plus extra for greasing
Put the water into the bowl of an electric mixer and sprinkle the yeast over. Leave or 5 minutes to become foamy. Add the milk, flour, salt and honey and mix on low for 2 minutes. Stop the machine and let the dough rest for 2 minutes, then mix on low for a further 2 minutes.
Meanwhile, put the butter between two sheets of plastic wrap and beat it with a rolling pin until it is thin and soft. This will only take a few minutes.
Turn the mixer onto to low and drop small pieces of the softened butter into the dough, one at a time. Once all the butter is incorporated, turn the dough out onto a floured board. It will be silky-soft, but still able to be handled without sticking to everything. Fold it in half, then turn it 180 degrees and fold again. Fold it a third time, shape it into a ball and place it in a greased bowl, cover with plastic wrap and leave for about 3 hours to triple in size.
Punch the dough down and turn it out onto a floured board. Fold the dough in half, and repeat two more times. Put it back into the bowl, cover it with plastic wrap and leave for 2 hours to double in size.
Turn the dough out onto a floured board, shape it into a rough rectangle and roll it up into a log shape long enough to fit your pan. The dough is really floppy, but be confident and just get it in there. Flatten the top of the dough with floured hands, cover with plastic wrap and leave to rise for about 1 hour, or until it is about 1cm below the top of the pan.
Preheat the oven to 220C.
Slide the lid on top of the pan, or weight it down as described in the * note above, and bake for 40 minutes. Remove the bread from the pan and leave to cool completely on a wire rack before slicing.