Prepare all ingredients before starting to cook.
Place a medium (2-quart) saucepan or saucier over medium-low heat on the stove top. Add ghee or butter and garlic-infused olive oil and wait until the ghee melts.
Add flour and whisk and cook until well blended and smooth, about 3 minutes.
Increase heat to medium high. Slowly add milk, 1 cup at a time and whisking about 30 seconds between cups. Add salt and white pepper and continue whisking constantly until the sauce thickens, 4-5 minutes or until your desired thickness, but before the mixture starts boiling, keeping in mind that adding parmesan will further thicken the sauce. Remove from heat.
Add parmesan (see notes) and whisk until thoroughly combined. Taste the sauce and adjust seasonings as desired.
Use immediately in Low FODMAP lasagna Bolognese (or your desired dish) or store in an airtight container in the refrigerator after cooling until ready to use. It’s best when used immediately or within 24 hours but can typically last when kept in an airtight container in the refrigerator for up to 1 week.
