French Onion Boulangere Potatoes

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This has to be one of the most delicious potato side dishes in the world!

Prep Time20

Cook Time1 50

Total Time2 5

Course: Side Dish

Cuisine: French

Servings:

Author: Chris Collins

Cost: £1.50 / $2

Equipment

Sharp Knife & Chopping Board
Large Non-Stick Pan & Wooden Spoon (for onions)
Medium-Sized Pot, Whisk & Jug (for stock)
Potato Peeler
9" x 9" / 23cm x 23cm Baking Dish
Cheese Grater

Ingredients

Onions

1 tbsp EACH: Olive Oil, Butter
600g / 1.3lb White Onions, thinly sliced
1/2 tsp Salt
1/4 tsp Black Pepper
2 large cloves of Garlic, finely diced
2 tsp Fresh Thyme Leaves

Potatoes

1kg / 2lb Maris Pipers/Russets, or other starchy/baking potato
600ml / 2 1/2 cups Beef Stock
2x Beef Oxo/Bouillon Cubes, crumbled
1 tbsp Cornflour/Cornstarch
1 tsp Worcestershire Sauce
2 tbsp Butter
120g / 4oz Gruyere, grated
Salt, as needed

Instructions

Add 1 tbsp butter and oil to a large non-stick pan over medium heat. Add the onions and fry until they begin to soften and just about start to take on colour (around 15 minutes or so). Season with salt and pepper, then turn the heat to low and continue gently frying until very soft, deep golden and a little sticky (around 30-40 minutes). With a few minutes to go, stir in the garlic and thyme. The lower and slower you fry the onions the softer/more caramelized they'll be, so don't rush the process.
With around 15 minutes to go, add the stock to a medium-sized pot over medium heat. Stir in the Worcestershire sauce and Oxo cubes. In a small bowl or pot to one side, mix the cornflour with 1 tbsp cold water then whisk that into the stock. Gently simmer the stock for 15 minutes until it starts to thicken (you should be left with 450ml liquid).
During this time, peel and very thinly slice the potatoes (approx 1/8"). Grease the base of the baking dish with 1/2 tbsp butter and dice the rest into tiny cubes. Preheat the oven to 170C/340F.
Layer 1/5 of the potatoes in the dish, overlapping slightly as needed to prevent gaps. Season with a pinch of salt, then top with 1/4 of the onions. Drizzle over 1/5 of the stock, then repeat with the remaining layers (remember to season each layer - see notes). Finish with a drizzle of stock then scatter over the butter.
Bake uncovered in the oven for 70 minutes, or until knife tender right the way through. Top with gruyere then finish under the grill until deep golden and bubbly. Rest for 5-10 minutes to allow the potatoes to finish soaking in the stock, then slice into portions, serve up and enjoy!

Video

Notes

a) Onions - Don't rush the process, it takes time to tickle out the natural sweetness from the onions to properly caramelize them. If at any point the onions start drying out or burning, just turn down the heat and consider adding a splash of water. This will also help scrape off any fond from the pan too. You can make these ahead of time, just allow to cool and tightly store in the fridge for up to a few days.

b) Salt - Potatoes soak up salt like there's no tomorrow, so whilst the stock will taste pretty rich and salty, it's needed. I typically end up using 1/4 tsp salt in total to season the individual layers.

c) Temp/Timings - You want to be on the safe side and bake for a longer time at a lower temp, just to full ensure the potatoes cook right through. Ovens are all slightly different too, so timings will vary slightly. If you find after around 45mins the potatoes are struggling to cook through then increase the temp slightly to 180C/350F. On the contrary, if you find the top is browning too quickly and the potatoes are too firm, just drop the temp slightly to 160C/320F.

d) Make Ahead/Storage - I do like to make these fresh, but you can make them ahead of time if you'd prefer. The potato just soaks up a fair bit of the stock as they rest and they don't come out quite as saucy. Still taste awesome though! Just cook as instructed then allow to completely cool and tightly store in the fridge for 3-4days. Cover in foil and reheat in the oven at 180C/350F for 30mins, or until bubbling hot through the centre. Can grill/broil the top again to crisp up if you want! Can reheat individual portions in the microwave for ease if you'd prefer.

e) Inspiration - Inspired by a recipe by Anna Glover.

f) Calories - whole recipe divided by 6.

Nutrition