For the muffin layer:

1. Combine all of the muffin ingredients in a blender and blend for 2-3 minutes or until smooth. The mixture is thick so you’ll have to stop a few times and scrape the sides down with a silicone spatula to get it going the first minute or so.
2. Preheat the oven to 350 degrees (F) and then start your streusel topping.

For the streusel topping:

1. Combine the melted butter, almond flour, sweetener, lemon zest and coconut flour in a small bowl and stir well with a fork until a crumbly dough forms.
2. Spoon the muffin batter from the blender into 8 large or 12 regular muffin cups (if you’re using foil or thin paper then place inside a muffin tin to support them) – or into a small loaf or cake pan.
3. Crumble the streusel topping in pea sized pieces over the top of the batter.
4. Bake on the middle rack of your oven at 350 degrees for 35 minutes (large muffins) or 25 minutes (average sized muffin) or 50 minutes (loaf or cake pan) OR until a toothpick or knife inserted in the center comes out clean.

For the lemon glaze:

1. Combine the erythritol and lemon juice in a cup or small bowl. Stir with a fork until smooth.
2. If too runny, add another tablespoon of erythritol (or more) until an opaque but still pourable glaze forms.
3. If too stiff to pour, add another teaspoon of lemon juice to loosen.
4. Pour the glaze over the muffins after they are baked and slightly cool. Serve warm or room temperature.
5. Store any leftovers covered in the refrigerator for up to a week.