Arrange the turkey in a shallow ovenproof dish. Melt the butter in a saucepan, add the almonds and toss until they are golden. Sprinkle the nuts and butter over the turkey.
Melt the butter for the sauce in a saucepan. Sprinkle in the flour and cook, stirring, for 1–2 minutes. Add the milk, a little at a time, stirring after each addition, then simmer for 2 minutes. Add the Cheddar and garlic, season to taste and stir until the cheese has melted, then stir in the baby spinach.
Pour the sauce over the turkey, then mix together the Parmesan, parsley and breadcrumbs and sprinkle the mixture evenly over the turkey. Bake in a preheated oven, 160°C (325°F), Gas Mark 3, for 30–40 minutes until golden and bubbling.