Bring a large pot of salted water to a rolling boil. Add the elbow macaroni and cook until al dente according to the package directions. Drain well without rinsing.
In a large saucepan, melt the butter over medium-low heat. Whisk in the flour and cook for 1 to 2 minutes until smooth to create the roux.
Slowly whisk in the whole milk followed by the heavy cream. Continue whisking until the mixture is smooth and begins to thicken.
Reduce the heat to low. Stir in the softened cream cheese until melted, then gradually add the freshly shredded cheddar cheese one handful at a time until completely smooth.
Mix in the Dijon mustard, garlic powder, onion powder, kosher salt, and black pepper. Stir until the cheese sauce is rich, silky, and evenly seasoned.
Add the cooked macaroni to the cheese sauce and gently stir until every piece of pasta is completely coated.
Let the mac and cheese simmer over very low heat for 2 to 3 minutes, stirring occasionally to allow the sauce to thicken slightly.
Transfer to a serving bowl and garnish with chopped parsley, extra cheddar cheese, or freshly cracked black pepper. Serve immediately while hot and creamy.