Preheat your oven to 220°c/200fan/425f/gas 7
Heat the olive oil in a shallow casserole dish or large pan over a medium heat (I like to use a pan which is suitable for using on the hob as well as the oven to make less mess!).
Add the sliced bacon to the pan and cook, stirring occasionally, until it begins to crisp, about 5 minutes.
Add the shallot to the pan and cook for 2-3 minutes until it starts to soften. Then add the leeks, the thyme and a dash of salt and pepper and cook for about 5 minutes, stirring occasionally.
Pour over the wine and reduce the heat a little. Stir well and allow to lightly simmer for 10 minutes. (Now is a good time to prepare the potatoes.)
Peel the potatoes and slice them to about 2-3mm thickness - it's best to try and make them as even as possible.
Sprinkle the flour over the leeks etc a little at a time and mix well to combine, then slowly pour in the chicken stock in 2-3 batches, mixing until smooth before adding more.
Add the mustard, sweetcorn and shredded chicken or turkey. Stir in half the cream, mix well, then stir in the rest of the cream.
Season with salt and pepper to taste, then turn off the heat.
Arrange the potato slices in a layer across the creamy chicken sauce, then sprinkle with a dash of black pepper and the grated cheese.
Carefully place in the preheated oven and cook for 35-40 minutes, until golden brown and crispy.
Serve and enjoy! I love this dish with a simple side of steamed greens.