Mix the first five ingredients (cereals, nuts and pretzels) in a microwavable bowl and set aside.
In a small microwavable bowl, microwave butter and white chocolate until melted. Make sure you stir every 30 seconds. This process should approximately take 1 ½ to 2 minutes.
Add sugar and salt and mix well. Pour over the cereal mixture and mix until evenly coated.
Microwave the mixture uncovered in a HIGH setting for 4-5 minutes. Make sure you stir every two minutes.
Spread on paper towels to cool for approximately 10 minutes.