Step 1: In a small bowl, dissolve the yeast and 1 teaspoon of sugar in warm milk. Let it stand for 5-10 minutes until foamy.
Step 2: In a large mixing bowl, combine the yeast mixture, remaining sugar, salt, eggs, butter, vanilla, and 2 cups of flour. Beat until smooth.
Step 3: Gradually add the remaining flour to form a soft dough. Knead on a floured surface for 6-8 minutes until smooth and elastic.
Step 4: Place the dough in a greased bowl, cover, and let rise in a warm place for about 1 hour or until doubled in size.
Step 5: Punch down the dough and roll it out to 1/2-inch thickness. Cut with a donut cutter and place on parchment paper to rise for another 30 minutes.
Step 6: Heat oil in a deep fryer or large pot to 350°F. Fry donuts for 1-2 minutes per side until golden brown. Drain on paper towels and let cool.
Step 7: Make the glaze by melting chocolate chips and heavy cream together until smooth. Dip the top of each donut into the glaze.
Step 8: Melt the mini marshmallows in the microwave for 15-20 seconds. Once slightly cooled but still stretchy, use your fingers to pull ‘webs’ across the glazed cobweb donuts.