Fill a medium saucepan with a ¼ ”layer of water at the bottom. Bring to a boil.

Add broccoli and boil for 4 minutes, stirring halfway through.

Drain broccoli and immediately rinse with cold water until all the broccoli is cold. Set aside.

Cook elbow macaroni according to package instructions in salted water. Drain, do not rinse, and set aside.

Mix flour and salt together in a small bowl. Set aside.

In a medium saucepan over medium heat, melt the butter.

Add flour mixture and whisk to combine.

Cook for 1 minute until mixture is slightly brown.

Add milk and whisk until the mixture is smooth.

Add sour cream (or Greek yogurt) and whisk until smooth.

Cook on medium-high heat until the mixture is thickened (about 3-5 minutes). Do not let it boil.

Once mixture is thick (sticks to the back of the spatula), reduce heat to low and add cheese. Whisk until cheese is melted and mixture is smooth. Taste and add more salt if desired.

Add cooked pasta and blanched broccoli to the pot of cheese sauce and stir until the sauce is evenly distributed.

Let it cool for 3-5 minutes or until the cheese sauce has thickened a little bit and sticks to the noodles. Stir and serve warm!