Preheat your oven to 350°F (180°C) and grease an 8x8 inch baking dish.

In a mixing bowl, cream together the softened butter and white granulated sugar until the mixture is smooth and fluffy, about 2-3 minutes.

Gradually add the plain flour, cinnamon, nutmeg, and salt, stirring until you achieve a crumbly texture.

Evenly press the crumbly mixture into the bottom of your prepared baking dish.

Bake the crust for 15-20 minutes, or until it's lightly golden at the edges.

Once baked, allow it to cool on a wire rack.

In a separate mixing bowl, whisk together the eggs and brown sugar until light and fluffy, about 3-4 minutes.

Add the maple syrup, heavy cream, vanilla extract, and a pinch of salt, mixing well.

Gently fold in a spoonful of flour to help thicken the filling.

Sprinkle the chopped walnuts evenly over the cooled crust.

Pour the creamy filling mixture over the walnuts.

Bake for 30-35 minutes, or until the filling is set and slightly puffed.

Allow to cool completely in the baking dish, then lift out using parchment paper and cut into 16 squares.