For Filling

1. In a large pot over medium heat, add butter and flour. Cook and whisk until butter is melted and the flour taste is cooked out - about 5 minutes.
2. Add in milk 1/2 cup at a time and whisk thoroughly. Continue to whisk until there are no lumps and the mixture starts to become thick. Add in milk 1/2 cup at a time until gone continuing with this method.
3. Once all the milk is added and is starting to become thick add in cheese. Stir until melted, making sure the bottom does not become scorched - you may need to turn the heat down to medium-low.
4. Once all the cheese is melted, add in your spices and stir.

For Filling with Frozen Broccoli

1. Steam the broccoli according to package directions.
2. Once cooked, drain water from the bag and add to cheese mixture, stirring to incorporate everything.

For Filling with Fresh Broccoli

1. Chop broccoli florets into small bite-size pieces. Add to a pot of boiling water and blanch for 2 minutes.
2. Once the broccoli is bright green, remove from boiling water with a strainer into a large bowl filled with ice water. This will help the broccoli stop cooking.
3. Remove from ice water to a large strainer after 2-5 minutes and let sit to remove as much water as possible then add to cheese mixture and stir together.

For Crust

1. Melt 1/2 stick of butter in a bowl.
2. Crush one sleeve of Ritz crackers and add to melted butter. Stir until butter is mixed with crushed crackers.

To Assemble

1. Preheat the oven to 350 degrees.
2. * Taste broccoli and cheese mixture to make sure the spices are right. Add more salt, pepper or mustard powder if needed.
3. Pour cheese mixture into a greased baking dish.
4. Pour crushed crackers over top and spread across evenly.
5. Place in the oven for 30 minutes.
6. Enjoy!