Slice tomatoes in half, scoop out the seeds and discard. Season the tomato shells and scatter with thyme leaves. Drizzle the tomatoes with a little olive oil and place under a preheated medium broiler for ten minutes.
In the meantime prepare the Hollandaise sauce. Melt the butter in a saucepan. Put the egg yolks and a splash of water into a blender or food processor, along with the lemon juice. Season well.
Blend the ingredients together, slowly adding the hot butter to the mix as you go, little by little. Continue to blend until sauce thickens. Set aside.
Fill a large, shallow pan with water (about 2in deep) and bring to a simmer. Add some vinegar (1-2 tbsp per 4 cups of water) to help the eggs hold their shape. Then break four eggs into separate coffee cups (again to help maintain their shape when they're placed in the pan). Gently tip the eggs into the simmering water and poach for 2-3 minutes.
Meanwhile broil the bacon slices until crispy. Slice the muffins in half and lightly toast.
When ready to serve place one tomato shell on top of each muffin. Break up one slice of the grilled bacon and sprinkle into the bottom of the tomato shells.
Once the eggs are poached, drain them on paper towels and place into tomato shells. Spoon a generous amount of Hollandaise sauce onto the eggs and top each with half a slice of bacon. Garnish with fresh thyme leaves.