Warm the milk in a small saucepan (no more than 40°C).
Dissolve the yeast in the warm milk with the sugar.
Add the flour and salt to a mixing bowl or the bowl of a stand mixer and mix.
Add the beaten egg and the milk/yeast/sugar mixture.
Knead for around ten minutes.
Add the butter and knead again.
Prove the dough for 1-1.5 hours a warm place (25 to 30°C) away from drafts: it should double in volume.
Divide the dough into 6 pieces weighing approximately 150 g and form 6 balls.
Place them on a baking sheet, spacing them well apart.
Brush with milk, sprinkle with sesame seeds, and flatten slightly.
Cover with a tea towel and let rise for 30 minutes.
Pre-heat the oven to 240°C. Lower the oven temperature to 180°C and bake for 15 minutes in the lower part of the oven.
2Balsamic vinegar ketchup
Peel, trim and finely chop the garlic.
In a saucepan, brown the garlic in the oil.
Add the tomatoes, sugar, balsamic vinegar and Herbes de Provence.
Cook over low heat for 30 minutes, stirring regularly.
Let cool before serving.
Peel the onions, cut them in half and thinly slice them.
In a hot oiled pan, sweat the onions until they turn translucent.
Add the sugar and continue cooking over low heat, stirring occasionally until they are browned.
In a bowl, combine the Greek yogurt and crème fraîche with the mustard.
Finely chop the pickles and add them to the sauce.
Add salt and pepper.
Preheat the oven to 210° on the grill setting.
Cut the buns in half and place them on a baking sheet, cut side up.
Form the steak mince into 6 balls and flatten them.
Heat a pan and brown the bacon.
In another pan, cook the burgers then add 2 slices of Raclette on top.
Put under the grill alongside the buns, letting the cheese melt.
Assemble the burgers: coat the bottom half of the bun with white sauce, cover with onion marmalade, add a burger with the melted Raclette, garnish with 2 slices of bacon, and finish with the top half of the bun spread with ketchup.
Serve immediately with chips and balsamic vinegar ketchup!