Prepare the Streusel Topping by mixing together 3 tablespoons of all-purpose flour, 1 ½ tablespoons of cold unsalted butter cut into cubes, 1 ½ tablespoons of light brown sugar, 2 teaspoons of granulated sugar, a pinch of salt, and ¼ teaspoon of ground cinnamon or pumpkin pie spice in a small bowl until crumbly.
Preheat your oven to 350°F (175°C). Line a muffin tin with paper liners or lightly grease it to prevent sticking.
In a medium bowl, combine 1 ½ tablespoons of full-fat sour cream at room temperature, 5 tablespoons of pure canned pumpkin, and 1 tablespoon of apple juice or orange juice with an egg yolk and ½ teaspoon of vanilla extract until smooth.
In another bowl, whisk together ½ cup plus 1 tablespoon of all-purpose flour, ¼ teaspoon baking soda, and an eighth teaspoon salt along with three-quarters teaspoon pumpkin pie spice until well mixed.
Gradually add the dry mixture into the wet ingredients until just combined; be careful not to overmix as this can lead to dense muffins.
Gently fold in the cubed fresh apples before spooning the batter evenly into prepared muffin cups before sprinkling each muffin generously with prepared streusel topping.