Soak the raisins in warm water for 10 minutes, then drain and pat dry. Whisk the flour, yeast, sugar and salt in a 4-liter / 4-quart bowl, then add the milk, egg and lemon zest and mix until a shaggy dough forms.

Add the softened butter in three additions, working each one in before the next. Knead for 10 minutes by hand, or 6 to 8 minutes in a stand mixer on medium-low, until the dough is smooth and slightly tacky. Knead in the raisins during the last minute.

Shape the dough into a ball and place it in a lightly greased bowl. Cover and let it rise at room temperature (22 to 24 C / 72 to 75 F) for 60 minutes, until doubled.

Line a 33 x 46 cm / 13 x 18 inch sheet pan with parchment. Turn the dough onto the pan and stretch it gently to about 28 x 38 cm. If it springs back, rest it for 5 minutes and stretch again. Cover and let it rise for 30 minutes until puffy, and heat the oven to 180 C / 356 F during the last 15 minutes.

Press your fingertips into the dough to make shallow dimples. Brush with 20 g of the melted butter and sprinkle with the 2 tbsp sugar.

Bake for 28 minutes, rotating the pan once at 15 minutes, until the top is deep golden and the center reads 93 C / 200 F on an instant-read thermometer. If the sugar or raisins darken early, tent the pan loosely with foil.

Brush the hot bread with the remaining 10 g melted butter. Slide it onto a rack and cool for 10 minutes before cutting into 10 rectangles.