Prepare the French Toast layer: Preheat oven to 350°F. Slice the bread into 1 ½ inch cubes and place in a greased 9x13 inch dish or large casserole dish. Set aside.
In a mixing bowl, whisk together eggs, sugar, milk, cream, vanilla cinnamon, ginger, cloves and nutmeg. Add pumpkin purée and whisk until smooth.
Pour egg mixture over the bread and toss gently to coat. Make sure the pieces on top are nicely coated. There will still be a bit of liquid in the dish as well, you can let it sit out to absorb more of the liquid if desired.
Prepare the streusel topping: Combine the flour, brown sugar, cinnamon, and sea salt and stir to combine. Add the cold butter, cubed, into the mixture and use a fork or pastry cutter to break down into small pieces and combine until the mixture is in small crumbles. You can also use a food processor for this step. Add the pecans and toss.
Sprinkle the streusel topping over the pumpkin French Toast mixture evenly. Make sure as few of the pecans are exposed so as not to burn.
Bake for about 45-55 minutes or until the French Toast is puffy, golden and the center is not too wet. The streusel should be a golden brown as well.
Remove from the oven and allow to cool for about 10-15 minutes before serving. Serve with a drizzle of maple syrup or even whipped cream!
Store leftovers in an air tight container for up to 5 days in the refrigerator. You can freeze this casserole as well.