For the oatmeal pastry, put the flour, oatmeal and salt into a food processor or mixing bowl, add the butter and lard and work together until the mixture looks like fine breadcrumbs. Stir in the water with a kitchen knife, or process briefly, until the mixture comes together into a ball. Knead briefly on a lightly floured surface until smooth.
Divide the pastry into 6 even-sized pieces. Roll each piece out on a lightly floured surface and roll out into approximately 15cm discs. Use to line 6 lightly buttered 10cm tartlet tins that are 3cm deep. Chill for 20 minutes.
Meanwhile, preheat the oven to Gas Mark 6, 200ºC (400ºF). Cut the prepared butternut squash into 2.5cm sized pieces. Place in a roasting tin with the olive oil and some salt and pepper and toss together. Spread out in a layer and roast for 20 minutes or until just tender.
Line the tartlet cases with squares of crumpled greaseproof paper and a thin layer of baking beans and bake blind for 15 minutes. Remove the paper and beans and return to the oven for a further 5-6 minutes until crisp and biscuit-coloured. Meanwhile, heat a large pan over a medium-high heat, add the spinach and cook for 2-3 minutes until it has wilted down into the base of the pan. Tip into a colander and gently press out the excess liquid. Season. Break the goats’ cheese into small pieces.
Remove the tartlet cases from the oven and lower the oven temperature to Gas Mark 5, 190ºC (375ºF). Arrange the pieces of roasted butternut squash, spinach and crumbled goats cheese in the tartlet cases. Beat the eggs and cream together in a jug with 25g of the grated cheese and some seasoning. Pour into each tartlet case and sprinkle with the remaining grated cheese. Place on a baking sheet and bake for 20 minutes until set and lightly golden. Serve warm.