In a saucepan over medium-high heat, add the butter to melt. Once the butter has melted, reduce the heat, add the flour and stir to create a roux; the roux should be pale blond in color. Once the roux is made, reduce the heat again to low, add the milk, stirring into the roux and cooking until the roux has thickened. Finally, add the blue cheese, 1 cup at a time, until all the cheese has been added and well blended. Season with the salt and pepper blend. Remove from the heat and continue to stir to ensure consistency.
Once the sauce has been prepared, add the orzo, spinach and tomatoes and stir to incorporate into the cream sauce. Allow the orzo to warm with the sauce, then remove from the heat and serve. This has a shelf life of 5 days.