To make the dough, place the bread flour in a large bowl or the bowl of a stand mixer fitted with a dough hook, add the yeast to one side and the salt and sugar to the other, stir to combine.
400 g (3 ⅓ cups) white bread flour, 7 g (2 ¼ teaspoons) instant/fast action yeast, 45 g (¼ cup) caster or granulated sugar, 1 teaspoon table salt
Add the lukewarm milk and mix to form a shaggy dough. Knead with the mixer or turn out onto an un-floured surface and knead for 5-10 minutes until smooth and elastic. The dough will be sticky at first but resist the temptation to add extra flour, it will become smooth after a minute or two of kneading (you may need to scrape it off the surface with a dough scraper).
270 g (1 cup + 2 Tablespoons) unsweetened non-dairy milk (I use soy)
Add the softened vegan butter. Continue to knead until the butter is fully incorporated and the dough is smooth and elastic. It may seem greasy and messy at first but keep kneading and I promise you the butter will all mix in and the dough will become smooth.
60 g (¼ cup) vegan block butter
Once the butter is fully incorporated the dough should look smooth and silky and it should pull away from the work surface or sides of the bowl cleanly. It should still be soft and slightly sticky however.
Place the dough in a lightly oiled bowl, cover and set aside to rise in a warm spot until doubled in size, about 1-2 hours. Line a 2 lb loaf tin with greaseproof paper.
Punch down the risen dough and give it a brief knead to knock out any air bubbles. Roll the dough out on a lightly floured surface into an approx 30 x 45cm (12 x 18 in) rectangle. Use your hands to spread the softened butter evenly over the dough.
60 g (¼ cup) vegan butter
Peel, core and dice the apples and mix them together the brown sugar, cinnamon and cornflour if using. Do not do this step too far in advance as the apples will start to release lots of juice.
3 large eating apples, 100 g (½ cup) light brown soft sugar, 1 Tablespoon ground cinnamon, 1 teaspoon cornflour (cornstarch)
Spread the apple filling plus any juices evenly over the buttered dough.
Slice the dough widthways into 5 even strips (a pizza cutter is the ideal tool), then lengthwise into 4 strips, to make 20 squares of dough. Stack the squares into 5 piles, each with 4 squares.
Stack the dough piles upright in the lined tin, squashing them together to fit them all in. Gather up any apple filling that fell off and scatter it over the top. Loosely cover the tin, and leave to rise in a warm place for about 45-60 minutes until puffy.
Meanwhile, preheat the oven to 190°C/170℃ fan/375°F/gas mark 5.
Bake for about 50 minutes until the temperature in the centre registers at least 90°C/194°F on a probe thermometer, or a skewer inserted into the centre comes out clean, with no bits of raw dough on it. Loosely cover the bread with tin foil towards the end of baking if the top starts to get too dark.
Allow to cool for 15 minutes in the tin on a wire rack.
Meanwhile, make the glaze; sift the icing sugar into a small bowl and stir in the vanilla and milk. It should be a pourable consistency, add a little more milk if it is too thick or a little more icing sugar if it is too thin.
110 g (1 cup) icing (powdered) sugar, 1 teaspoon vanilla extract, 1-2 Tablespoons non-dairy milk
Turn the bread out onto a serving dish and pour over the glaze. Serve warm.