In a large pan, heat butter until it melts on medium.

Add onions and asparagus and cook on medium until softened and browned.

In a small bowl, add cream and flour and whisk well until clumps are gone.

When vegetables are soft and slightly browned, add vegetable stock slowly, while stirring.

Keep stirring vegetables and stock, and slowly add milk and flour mixture.

Add seasonings and cook on medium for 10 minutes, stirring occasionally, until soup base has thickened.

Remove from heat and add to casserole or a sterile jar with a tight fitting lid.

If keeping in the refrigerator, use within 2-3 days.