Pre-heat oven to 400°F. Prepare a donut pan (or 2 if you have 2) by greasing with butter and then sprinkling with flour.
Whisk together all wet ingredients (egg, melted butter, vanilla extract and yogurt).
In a medium bowl whisk together dry ingredients ( flour, sugar, baking soda and salt).
Combine wet ingredients with dry until just combined with a wooden spoon. The batter will be very stiff.
Fold in the diced strawberries.
Transfer the donut batter to a disposable piping bag and pipe into a greased donut pan. Bake for 8 to 10 minutes until donuts are slightly golden. Allow donuts to cool for 5 minutes in the pan and then invert onto a cooling rack to fully cool!
Prepare glaze while donuts are cooling. In a medium deep bowl, whisk together confectioners sugar, heavy cream and strawberry jam.
Dip the tops of the donuts in the glaze and return to a cooling rack with a cookie sheet underneath to set. Garnish with fresh strawberries if desired!