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					Preheat oven to 200C.
				 
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					To make the béchamel, melt butter in a medium saucepan, add flour and cook until lightly toasted. 
				 
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					Add milk slowly, whisking constantly and simmer and stir until thickened. Season with salt.
				 
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					Cook onion and bacon in a medium frypan.
				 
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					Into a large pot of boiling salted water, add the pasta and cook as per packet directions.
				 
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					Oil a 2L capacity baking tray, add cooked pasta, onion, bacon, cheeses and chopped spinach.
				 
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					Season with salt and pepper and toss to combine.
				 
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					Pour over béchamel and stir to mix through.
				 
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					Place tray in oven and cook for 30 minutes, or until golden and bubbly.